Swagbucks. Swagbucks pays you to do what you already do - search on the internet. Each time you search using swagbucks, you can earn swagbucks that can be cashed in for a variety of gift cards or prizes. To join click on the box above and start earning.
I cash out for about $25 or so a month, which I use to get Amazon gift cards to buy books! The picture above is my latest Swagbucks purchase.