I discovered Ebates a few years ago when I had developed the habit of looking for online coupons whenever I was shopping on the computer. Usually I was trying to find a free shipping deal or % off my total purchase. By going to Ebates before I shopped, I often found coupons and then the bonus of a rebate in cash back to me for shopping through their link. Last month, with a few simple purchases through Barnes and Noble bookstore and Home Depot I earned $13.00. I was already going to shop at both places and by visiting the site through Ebates, I saved money using free shipping coupons and then also received the additional cash back.
Its very easy to join. Go to Ebates and sign up. Then, when you are going to be shopping, go to their site and look for the store you want to use. Click on their link to the store and they track your purchase. If you complete a sale, they will then process a rebate for you. If you are using an email coupon, use that link and when you have the items in your cart, go to ebates in a different window and then find the store and use their link. The items should be in your cart and now you have the additional rebate.