Check bitrefill.com to see if your SIM card can be topped up with bitcoin using their service.  They cover many countries.

Bitrefill would be smart to also sell (where legal) unregistered SIM cards for bitcoin.

I would love to see what you've done. 

I really think that future of decentralized home mining depends on also using the heat.

Here's a simple back-of-the-napkin calculation - I would be curious to hear if people think this is wildly unreasonable or not.

Let's say the whole thing costs you $1500 to build a 1000W system and you spend about $1700 in electricity for the season (Nov - Feb @ 24h x 30 days x 4 months x 6 cents per kwh) to run it.  As long as your mining efficiency is better than break even for the power you'll make $1700+ in bitcoins.  Assuming you were going to  have to burn that electricity anyway for heat, your net cost is $1500 instead of $1700 for the season. 

Next season you only swap the mining boards so your cost is $1000 for 1000W, but you can reuse the $500 radiator unit.  Assume you again break even, now your net cost for the season is $1000.  Or, if instead you keep your old boards which are now mining at a 50% loss, then you spend $1700 in electricity for 1000W of heat and make $850 of bitcoins.  Either way, you cut your power bill down from $1700 to $850 or $1000.

If the bitcoin price goes up, your mining efficiency is > break even on power or you can use the heat all year (eg. to augment a water heater) then the economics look even better.  If the bitcoin price crashes or mining difficulty increases faster than expected, you'll lose - but nothing ventured nothing gained. 

This isn't a get rich quick scheme, this is a get rich slow scheme.    And hopefully fun; people spend much more to overclock their home PCs with no financial gain.

The three financial caveats you need to accept are:

1) you were going to spend the electricity for heating anyway (24x7 during the coldest months)
2) your mining revenue is greater than, or equal to your electricity costs to run the mining boards (during the season)
3) the up-front cost of the mining boards is less than the cost of a season of electric heating

Notice that the only real unknown is the mining revenue.  However, it is safe to say that the expected return for any mining boards should be greater than the cost of the electricity or else no one would even consider buying it.  From a strict business perspective, the mining operation still runs at a loss of the invested capital ($1000) even if you break even on electricity.

A clever accountant might also recommend you treat the whole thing as a home business.   Then you can deduct the cost of the mining equipment and electricity against the bitcoin revenue and deduct the loss on your taxes for a few years.

Please let me know where my math is wrong; I know I am taking a big risk by proposing a profitable scenario in this forum. :-)

As feature sizes get smaller and chip density increases air cooling is going to be a losing proposition.  Some sort of passive liquid cooling is the ideal way to do it, especially if you want something that your wife will let you put in the living room.   

The ideal heat exchanger / radiator would allow you to easily swap out obsoleted boards for new ones.  That way you could amortize the heater over multiple generations of mining hardware.    Even better is enough room to keep older generation mining and just add new next generation boards so you can squeeze the last coins (and heat) out of old hardware.

All mining rigs are going to need the same thing - power, ethernet and cooling; the rest is just mounting.  So in theory the radiator part can be fairly universal.

I am sure if we could put a group together interested in home heating from bitcoin mining that we could get an affordable and elegant device made specifically for this purpose.

What I am thinking of is something clean and quiet that could sit on the wall in the living room or den and not have to be hidden in a closet.  Another option would be a device that hooks into a hydronic water loop heating system.

I'd like to start an interest list and make this happen, but we need a large enough group willing to invest in such a system to make the economics work out.  If we could get one of the mining rig firms interested that would also be helpful.  I've made some back-of-the-napkin calculations and I think the goal of nearly free heat is very attainable, even accounting for the initial investment in the mining hardware and heat exchanger.

I'm looking down the barrel of a nordic winter so I could use this kind of system today.  Who's with me? 

Ideal candidates for this system have the following characteristics:
 1) already using electricity for home heating
 2) long and cold winters
 3) own their home

The folks at Nerdalize are developing computational heat exchanger modules specifically for home heating that would be perfect for mining also.  They use general purpose computers for the computation/heat source, but  I have talked with them about adapting their technology for Bitcoin mining.   They are interested, but they would need a large enough order to justify adapting their modules for bitcoin mining.  They have already run evaluations of a KnC Jupiter mining board and their systems could easily handle the high power/heat densities of bitcoin mining chips.  They just need to see customer demand to justify more work in this direction.
 
One thing to keep in mind also is that mining is about to start running into Moore's law.   That means we could see 20 nm mining chips stay competitive longer than 28 nm chips, and future feature sizes even longer.

This could also be a way to decentralize Bitcoin mining which now seems to be dangerously headed towards data center centralization.

Wouldn't it be simpler to provide Bitpay with an encrypted version of your name/address information for the invoice using the merchants public address as the encryption key?  Bitpay could store the encrypted information in case of a dispute with the merchant; the merchant could use the (decrypted) information for shipping and in the case of a dispute Bitpay could verify the correct address was sent to the merchant by looking at the information provided from the merchant and checking that it was signed by the customer.

These sorts of protocols have been possible for decades (thanks to Phil Zimmermann and others) but what has been lacking is the motivation to use them and an easy way for people to manage their public/private key pairs.  Bitcoin wallets provide both motivation and easy of use.

BitID is an important step towards the dream of public-key cryptography becoming a ubiquitous part of daily life.  Right now it's convenient to log in to new web sites using twitter, facebook or whatever social login, but why should I include them in my login process at all?   Anyone with the capability of managing their own keys can create a unique pair for every site they visit using BitID.  Or you can use one pair in cases where you want to establish a common identity across sites.

This BitID project is both simple and very important.

We need more development of person-to-person exchange tools that take advantage of Bitcon's distributed nature. 

Centralized exchanges like Mt.Gox are relatively easy to setup and use.  People have to cough up intimate personal details to satisfy KYC rules and trust the operators to not lose or steal their money, but otherwise they are a rather familiar model for most people.

Early p2p exchanges like bitcoin-otc had the right idea from the start, but has not evolved into something the great unwashed masses of non-technical people are capable of using.

The localbitcoins exchange is something more user friendly, but also more vulnerable to attacks because of centralization.  The recent Florida arrests show that they are on the radar of law enforcement and this type of exchange could easily be shut down by authorities in places like China and Russia.  People are also reluctant to exchange in person and any online person-to-person exchanges require escrow and trusted identies. In the case of localbitcoins.com escrow just moves the risk back to a central web site.

A few new efforts such as bitrated are starting to leverage features of the Bitcoin protocol to facilitate truly distributed exchanges.  I hope we see more projects moving in this direction.

A few big highly regulated exchanges might work OK for the 1st world, but the more financially oppressed developing world desperately needs person-to-person options before their governments start waking up to what Bitcoin means for them.

Under this potential tax treatment, someone using localbitcoins to sell bitcoins would be the equivalent of someone using blocket to sell a car, right?  My understanding is MOMS is charged for profits from sales on blocket only above 50.000 SEK (7,500 USD).  Only if you are a regular seller of something would you need to report to the tax authorities your yearly profit from person-to-person sales, and that profit would be taxed at a 30% rate. 

From Blocket.se:

     Sale of individual items

     If you sell goods on any single occasion, then the possible profit that exceeds SEK 50 000 is taxed at 30%.

     Profit is the difference between your purchase price for the goods and the price you then sell the item for. If you have received or inherited what you sell, it is the previous owner's purchase price you should count on. Do not you know the purchase price can make use of a standard value which is 25% of your selling price.

If I were you, I'd start investigating escrow companies and find one willing to handle a Bitcoin transaction.  There is little risk of fraud if the escrow company (properly) handles the deal.  Perhaps investigate using a 2 of 3 transaction, but honestly a paper wallet might be easier unless the Escrow company is very savvy.

Update: I  am withdrawing my offer, and will be using ShopandBox to get the phone from Australia with fiat instead.  In the final analysis, I'm not ready to part with my precious bitcoins just yet.

On a side note, I had an interesting discussion with ShopAndBox and they seem willing to investigate adding a Bitcoin payment option.   I think it would be very complimentary to their business model, as it would also be for AirBnB, Uber and any other international person-to-person style business.

It's hard to say now whether or not using CoinsforTech or Francong with escrow would have been a better deal, but the personal service I received from ShopAndBox gave me the confidence to pull the trigger.  Trust is always an issue when buying over the internet, and especially when paying with bitcoins.   Easier to use escrow services and reputation systems would help.  Wild fluctuation in the bitcoin exchange rate also makes it harder right now to use bitcoins, but I expect that will become less of a problem over time as the market depth grows.

Update: even cheaper on the Australian play store.

Australia Play Store - 449 AUD ($419)

Would love to be able to arbitrage these different play store prices using Bitcoin.  Just need a reliable bloke from down-under to help me out. 

I would like to buy two Black 32GB version Nexus 5 phones made for "Rest of World" (RoW) sold outside of North America.  Model number LG D821.  Shipping to North America (California).

I have seen the following international prices:

India Play Store - 32999 Rs ($528)
European Play Store - 399 EUR ($537)
Hong Kong Play Store - HK$3,588 ($462)

Ideally I would like to order it from someone able to buy from the Hong Kong play store who could then add handling fee + shipping.  I will pay in Bitcoin with escrow, at the exchange rate defined by the BitcoinAverage.com USD price (without Mt.Gox).

So for example,  assuming Hong Kong play store seller:

3588 HKD - phone price
  300 HKD - handling fee + shipping to USA
-----------
3888 HKD -> 502 USD (as per Google)

$502 / 579 BTC (bitcoinaverage.com USD average without Mt.Gox on 11/20/2013 @ 9:42 AM PST) -> .867 BTC

So in the above example, I would be willing to today pay .867 BTC to escrow for one Black Nexus 5 D821, including shipping to USA.   Actually, if I can find the right price I would be willing to buy two phones like this, so it would be 1.734 BTC to ship two LG D821 phones to USA.

For someone who wants to acquire some BTC at a favorable rate, this is a good deal I think.    This is an experiment to see how I can use escrow to buy with Bitcoin person-to-person.   I would not want to pay more than I can buy it for Bitcoin via an online retailer that accepts bitcoin.  Currently CoinsForTech has the phone for .98 BTC + shipping.

I am a recent Slush pool member and former BTC Guild member.  I prefer many things about how BTC Guild reports statistics, but the increased centralization of hashing on any pool seems detrimental to the long term value of my coins. 

I have what is probably a naive question that I think many new miners might share.

In a nut shell, when someone gets a shiny new ASIC, they know the coins it will produce are front loaded - the difficulty is going up, so they want low variance so they get the benefit from the maximum theoretical reward of their device with out the risk that bad luck/reward variance causes them to miss reward when network difficulty is low.

Has anyone quantified the relationship between the pool hashrate and network difficulty for an individual member's hash rate as it relates to the desire to get maximum reward as early as possible?

So far my daily payout seems comparable to BTC Guild.  I assume the higher a member's hash rate then the less they need to join a big pool to receive low variance rewards up front.  I think if this is true (and could be explained well) maybe people would spread their hashing around a bit more and not just flock to the largest pool.

My intuition tells me you can somehow compute the theoretical variance from a large pool vs. smaller pool for a particular hash contribution. 

An example (with bogus numbers) of what I'd like to see a report on might look something like this:

Small pool (Slush):

 - Expected daily reward with for 700 Gh/s member is 0.70 +/- 0.5  BTC/day (SD = 0.1) for pool with 5% of hashing power and network difficulty of 510,929,738.02.

Large pool (BTC Guild):

 - Expected daily reward with for 700 Gh/s member is 0.70 +/- 0.2 BTC/day (SD = 0.01) for pool with 35% of hashing power and network difficulty of 510,929,738.02.

Solo mining:

 - Expected daily reward with for 700 Gh/s member is 0.70 +/- 17 BTC/day (SD = 1.2) and network difficulty of 510,929,738.02.

My statistics fu is not up to the task, so hopefully someone has already figured out the equation 'f' that returns:

  (avg return, std deviation) = f(miner hash rate, pool hash rate, network difficulty)

Even better would be if you could solve to find the minimum pool hash rate that gives a miner with a fixed hash rate a minimum desired standard deviation on BTC return within some time frame (eg. 1 day).

For the smallest miners, the largest pool is best to even out average payouts and take advantage of current (lower) difficulty.  But for larger miners I suspect it is more nuanced and you only need a pool that is over some threshold to get the benefit of being in a pool.  I know pool fees and details are also important, but I am ignoring that for this analysis.

I'd like to know more about how sending cash in the mail works in general.  How are the buyer/seller protected by escrow?

There seems like no way for the escrow agent to validate that the buyer of BTC actually sent the cash, unless the escrow agent receives the cash and forwards it to the seller.  This can create a certain counter party risk from the escrow agent.

At least with cash-in-the-bank transactions there is some receipt given by the teller.

It sounds like SaltySpitoon has some experience doing this so I'm curious how fraud is prevented.

Same call from +1-866-723-3108.  If someone wants my code, it's bfl-590347 for 20% discount.

But anyone reading this thread probably will want to think twice before buying into their death spiral.

There is an interesting discussion about using airports for otc transactions that would serve foreign visitors needing local cash.

Even better would be taxi drivers (or their agorist ride share equivalent) who accepted bitcoins and who could also do a side business exchanging fiat for bitcoins.  Deals would likely have to be arranged in advance, like a driver service, for the safety of both drivers and the passengers.

Order number: 12xx
Date of order: 5 Jun
Number of Jupiters: 1
Pick Up: Hosting
Estimated shipping day: day 1

I think you are right.  It's a legacy of learning to type at a certain time and place.  I distinctly remember my typing teacher (teaching us to use an IBM Selectric typewriter) telling us to put two spaces between sentences.  This probably dates Satoshi (and the rest of us) as having learned to type with an older typewriter standard, OR from someone who taught an older typewriter standard.   More conclusively though it places Satoshi as having learned in an English speaking country.  Apparently no non-English speaking countries do this double space thing, according to: http://www.ditchwalk.com/2011/01/19/two-spaces-after-a-period/ .  But no one suspected Satoshi as actually being Japanese anyway.

Here's an interesting development:

https://bitcointalk.org/index.php?topic=252238.0

.