Shopping online is something that you probably do all the time. So once you buying something you might as well take advantage of getting cash back. I'll show you how.

 Click on this link and set up your account. When you make a new account you get to choose either a $10 gift card to Barnes & Noble's, The Home Depot, Target or or you can get $5 after you first use Ebates. (I picked the $5 since I didn't have any use for the gift cards, but that would depend on each persons preference.)
The other thing that is worth mentioning about Ebates is that if you refer someone than you get $5. That being said, please do me a favor and please follow my link :-).

Other Cash-Back websites
Big Crumbs (They also give commissions when you refer others.)
Mr. Rebates (They offer a $5 sign up bonus and they also give commissions when you refer others. )
Coupon Cactus (They offer a $3 sign up bonus and they also give commissions when you refer others. )

How do I which one to use?
 I don't know if there is a general rule, but you should check out this Cash Back Chart to get an idea.

 Good luck and don't forget to refer me!