There are a lot of rebate sites out there. I have signed up for a few. However, I really don't want to sign up with anymore unless the are offering a great deal on something. Anyway, while I was looking at rebate amounts tonight, I came across this website.
You can type in which store you are shopping at, like Target, and it will tell you the rebate being offered by each of the rebate sites. Target had rebates between 3% and 5.6%. There were also stackable coupons listed.