Meera got me onto this. Ebates is a portal that refers you to online shopping. Because you use them to refer you, you get money back. They send you a cumulative check every three months. They also offer additional coupons and discounts.
For instance, I just bought some books at Barnes and Noble, just enough to get free shipping ($25), and Ebates wil give me $1 for that. Two weeks ago, I used an Ebates coupon on Champion sportswear, and I got $3.79 from Ebates. (I spent about $63.) It's not a ton, but it adds up, especially if you already shop online.
You have to sign up, but you get $5 just for signing up (and another $5 for your first purchase), and I get $5 if you sign up through me.
Check out their website here, then sign up through me by clicking on the banner below.