Have you heard of RetailMeNot? No? It's one of my favorite sites! It has coupon codes available for over 65,000 stores!
One of my best saving money trick for shopping online (besides using Ebates for every purchase, if possible) is going to Google and typing *store you are shopping at* and coupon code. At least 90% of the time, I find an offer that I can use for my purchase, and most of the time, the coupon code is on RetailMeNot. You can use these coupon codes to save extra money, in addition to the cash back in your Ebates account!
Another fun thing about RetailMeNot (well, I'm an online dork) is sharing the codes. If you sign up on the site, you can track codes shared and money saved using the site. I like to submit any coupon codes I can find, and since I've been using the site for almost a year now, I've submitted 257 codes and according to the site, saved others $33,066! When you use a coupon code to make a purchase, if you check "it worked for you" it will ask you approximately how much you've saved.
So, next time you make a purchase online, I suggest checking out RetailMeNot!
They also have printable coupons, and shopping tips for your favorite stores!