Bitcoin is, as far as I know, unique among digital currencies because of its decentralized nature, where you don't need to trust anyone in particular, but just need to trust that 51% of the hashing power is honest. It does have however serious scaling challenges and the ever-present problem of delays before transactions are confirmed.

Many other solutions instead require a trusted mint to issue coins, which then allows to do very fast transactions. Lots of thinking and cryptography has gone into these systems to give them additional nice properties. Especially "Chaumian blinding" is a key technique here, as far as I can tell, which prevents the central mint from knowing too much about the people that it issues coins to: If Bob gets some coins from the mint, then buys something at a sex toy shop and the shop then redeems the coins with the central mint, then Chaumian blinding prevents the mint from concluding that Bob was shopping at the sex toy shop.

The Ripple project is yet another approach to the trust problem: Here a trust chain between people needs to exist. (I trust a friend who trusts the person I want to pay.)

I think Bitcoin will pretty quickly face serious scaling issues and it seems to me, that some of these technologies could be a great complementary solution. Imagine having a (more-or-less) trusted central mint, where you could exchange Bitcoins for Fast-Transaction-Coins. With those coins you can now do fast mobile payments and extrem micropayments and whatnot, and at the end of the day (quite literally) exchange them back to Bitcoins. If you only keep a small amount of Fast-Transaction-Coins at any given time (like petty cash), you don't even need to have that much trust in the central mint, because you would have limited losses should the mint disappear or abuse its position.

So my question is: Which project would you consider the best fit to interface with Bitcoin in such a way? I guess it would make sense to leverage existing open source code in building something like that. Here is a nice overview of various digital currency projects: http://disattention.com/78/digital-currencies-crypto-finance-and-open-source/

My personal thoughts on this:

I think Ripple is very interesting, but I am not convinced that the "trust chain" works well enough for arbitrary situations. I just want to buy something from some random online shop without needing to figure out a trust path to them.

Open Transactions seems like a very interesting project, but suffers a little bit from too much complexity. Because of that, I haven't fully understood it and have the feeling, it tries to do too many things at the same time. But maybe a simple subset of Open Transaction would be a good start. And I believe the author has started on some "Bitcoin to Open Transaction" solutions already: see https://github.com/FellowTraveler/Moneychanger/wiki

Links to the options mentioned in the poll:
Open Transactions: https://github.com/FellowTraveler/Open-Transactions/wiki
Ripple: http://ripple-project.org/
Lucre: http://anoncvs.aldigital.co.uk/lucre/
OpenCoin: http://opencoin.org/
Loom: http://loom.cc/

What are your thoughts on this? Do you think making Bitcoin the backbone system too a low-latency, high-volume counterpart is a worthwhile goal, even if it introduces one or several centralized exchange points?