I cant imagine drugs make up a significant portion of the BT economy, speculation/money transfers alone seems to account for most of it. I suppose the only way to know is if one of these drug sites go down and we see the impact on the trade volumes.

Frankly if we are going to get this market off the ground we have to trust SOMEBODY.  I like your guidelines.  If you know where and who the person is, you have a leg up in litigating your funds back (since bitcoins do have an estimate-able value, theft is a criminal action.)  Another thing you should require is a merchant agreement.  When you are making a purchase online you want there to be a page (or better yet, receive and e-mail) that says exactly what product or service you are receiving and the cost in bitcoins.  You also want this to include the deposit address for the wallet, so you can prove that you paid to that address the specified amount from your transaction history. (print off the webpage.)

Another important factor is if they accept cash transactions.  In the United States and many Western Countries cash is legal tender, required by law to be accepted for transactions.  If they do not have a method for you to buy their product using a cash method, such as paypal, credit card, Western Union, etc, and operate solely on bitcoin then they are operating illegally.  Even if they are legitimately offering products and services you are taking a gamble that they won't be closed down through legal channels before filling your order, and probably shouldn't be trusted anyways for their complete lack of business sense.

Edit http://www.treasury.gov/resource-center/faqs/Currency/Pages/legal-tender.aspx Apparently private businesses in the US are not required to accept cash, but it would definitely be a step towards their credibility in my opinion.  Since fraud with legal tender is a federal offense and raises the stakes quite a bit for criminals.

Not secret!

I've ran a 'Free Second Life Linden' site since 2007, and I'm basically going to open one up for BitCoins soon. Where users do things like watch youtube videos/ads, facebook LIKE pages, complete offers, register to sites, etc. and earn BitCoin. In addition to BitCoins users could also withdraw the earned rewards to Second Life, or redeem for amazon gift cards, etc. The site is done, minimum withdrawal is 0.01 BitCoins. I just need to buy/trade for more. Ive traded $L for some, but need more to be on the safe side. On average I'd assume most users would only be able to earn like 0.25 BTC, more only if they put in a lot of effort in 'Tasks'.

Other sites I was thinking about were an online casino where users could compete in skill based games to see who gets the highest amount of points. I'd also like to try my hand at a marketplace.

Those are probably the best three ideas I have. The codes all done from previous projects. Ive had lots of random virtual currency websites over the past few years, so its basically just reworking them for BitCoins and seeing if theres any interest.