There is also
https://btcjam.com/. You have more old school trust here because the borrowers are vetted and confirmed to an extent. I've been considering putting a little money here. Also nice because you can help bitcoin businesses with your loan.
Still should be very cautious though. Start small and see how it works.
I would argue that bitfinex would be much safer then btcjam as the collateral is secured on the exchange. BTCjam basically uses reputation to give trust to it's members.