Agua Points (iOS only for now) is a more altruistic money earner as their end game is to help build water wells. Their own earnings are used towards the water well building campaign.
How it works:
Download the app, set up your account, lock your screen, and then it starts earning points. The longer your iPhone (Android app coming soon) is locked, the more points you earn. They do not award points 24 hours per day, but for the normal daytime hours you would normally be using it, as you are basically giving up your use of it to earn points and support their cause.
When you earn enough points, you can buy gift cards to any store they have listed (1200 points = $10 Amazon gift card, for example).