When shopping online you should either be shopping through a cash back site or through your frequent flyer miles provider site. No need spending more than you have to right?
So what happens when you use a cash back site is: you go to the cash back site and click on the store you want to shop at (it usually tells you the % back you get prior) then you shop like normal when you check out you will pay full price. However, within a couple of days you will get a email letting you know that your account at that cash back site was credited that %. Usually the sites have a cashout amount of $20. So, when you get your rebates to $20, you can cash it out to your Paypal account. Some do offer the option of a check. I think after all my Christmas shopping I got back $150.
Now...don't expect to get rich quick but a little bit here and there really does add up. Especially if you have a cash back credit card you use for online purchases. Use it together with the cash back sites. Just make sure you pay it in full each month!
These are the sites I use:
(gives you a $5 bonus to sign up and also tells you online coupons the store currently has)
If you use others, please share