Here's something I found interesting: Micro banks. Two examples are Prosper (US only) and Zopa. (UK only) (via Consumerist and Wandering Indian Monk)
These are websites that coordinate person-to-person loans. Unlike banks, individuals do not operate under a bureaucracy with lots of overhead and are not driven as much by profit considerations, so in theory anyway, an individual could offer a better interest rate than a bank's unsecured credit card division. So if you have a high interest rate on a credit card and can't find a better deal, you can check a micro bank to see if you can get a cheaper loan to lower your interest payments.
On the flip side, I don't think micro banks are good places to invest your money as a lender, so I have to disagree with Wandering Indian Monk on that part. I don't know what legal recourse you have if the borrower decides not to pay and with no collateral, there's nothing holding the borrower to the loan, except maybe the threat of a lower credit rating. And besides, if you're going for the yield, there are a bunch of funds and income trusts out there yielding 10% or more. (Run some stock screens and see.) However, if you really do want to try lending money, see if you can get 12-15% and diversify across a bunch of loans by lending each one a smaller amount of money.