I just tried this method (unfortunately I had an issue that I'll explain later) and I was wondering if anyone else tried it or if there are any problems with it.
1. Open a Virwox account and fund it with Paypal or credit
2. Trade USD for SLL
3. Withdraw SLL to your Second Life account
4. Open a Rock Trading Company account and deposit SLL from your Second Life account there
5. Trade SLL for Bitcoin and withdraw
Virwox charges $0.49 + 3.5% to deposit funds by credit and 2.9% to exchange USD to SLL. Virwox doesn't charge to withdraw to Second Life and I don't believe Rock Trading charges any fees for these transactions. However, Rock Trading has a very large spread for SLL <-> Bitcoin.
If you were to trade $100, it would cost $7.76 in fees and you'd get BTC11.66 ($8.58/BTC) using current bid prices at Virwox (262.6 SLL/USD) and ask prices at Rock Trading (2100 SLL/BTC). Not too good, but the ask price at Rock Trading is very high right now.
When I tried it, I couldn't deposit SLL to my Rock Trading account. Apparently, Second Life has this "Risk API" that prevents newly created users from exchanging SLL for other currency. I don't know the details, but you have to at least have made a real money transactions 30 days beforehand. I ended up trading privately with another user.
What do you guys think?