A while back I was about to try something along the lines of this site, but I noticed that along with someone signing up with your referral code, each person who uses your code also has to participate in one of their offers (which generally involves buying a product from one of their sponsors) before the point is given to you. In the end, they're making only slightly less than they're giving away, and the profit comes from people buying a few and giving up before cashing out.