Really? You're happy assuming a risk of an unsecured loan for the possibility of mediocre returns?
Unsecured, yes, but Prosper does an excellent job of collecting. This isn't just you lending money to some stranger and crossing your fingers. They are all screened by prosper and have to submit several documents in order to open an account. I'm pretty happy with the results.
I have nearly $2,500 invested and got a 16.8% return for 2012. Out of nearly 60 loans I've contributed to, 3 of them have gone into collections. Of those 3, I have received all of my money back on 2 of them, while one is still in collections. I contributed $25.00 to that one and the borrower paid me back 18.00 before going belly up. The other 57 or so loans are all paid on time impeccably thus far.
In contrast my other investments (IRA, Mutual Funds, etc) barely did 4% last year.
Prosper is actually pretty reliable if you don't put all of your eggs into one basket of course. I'd much rather have it there than a CD or some shitty savings account. I don't contribute more than $50.00 to any single loan and I keep a good mix of HR and A+ ratings. I also don't invest in any loan more than 1 year and more than $3,000. Since 2011 I've done pretty good. Probably going to push it up to $5,000 by the end of this year.
I've done plenty of research on it so if you have any questions, please feel free to ask. I asked TONS of questions before getting into it.