P2P lending and cloud mining are the first things that come to my mind. Lending can be risky, so you need to be sure of who you're lending to. It's definitely safer than gambling though..
Have you tried btcjam? Or another website? I have long wanted to try P2P Lending. I have been registered there, but never lent someone money.
I would have invested already, but I keep reading how there is a lot of people complaining about people not paying back the loans, let alone the interest, and BTCjam does nothing about it..