Gambling does not work on the average - nobody has free money to give away (of course, some sites get ad revenue and redistribute part of that to visitors, that's a bit different).
Betting might work a little better - I found that by betting on pretty certain outcomes (i.e. "bitcoin price will be over $50 on December 15") you can still make small gains in the long run - it's better than the interest paid by my bank, but not extraordinary, so I just do it for fun. Betting small amounts on real-world events is a relatively slow process, and I don't think it triggers the "gambling addiction" area of your brain...
If you're not afraid of dealing with Ripple you might check out
Computing for Good. Ripple Labs is sponsoring a grid computing effort (
World Community Grid) by handing out XRP for WCG points if you join their team - After just a few weeks they are already the biggest WCG team...
Since I was already interested in Ripple and had participated in another grid computing project a while ago I gave it a try, and my measly i3 CPU has already gotten me quite a few mBTC.
Onkel Paul