I personally try to use a rebate site any time I make an online purchase.
These sites work by paying you a part of the affiliate percentage that they get for you clicking through the links on their site to make purchases.
For example if you click on a link through their site to Priceline.com to buy a $500 plane ticket, they get 2% of your purchase for referring you ($10) and then they give 1.5% ($7.50) of it back to you and keep 0.5% ($2.50) for themselves.
Each store has a different percentage that you get back, for example BestBuy.com is 1%, Priceline is 2% and Overstock.com is 4%.
Most of them have a minimum of $10 to $25 of accumulated cash back from purchases before you can request a check.
But as an added bonus, they give you $5 free in your account just for joining. This means you only need to accumulate $5-$20 of cash back before you can get a check.
I highly recommend giving these sites a try. You have nothing to lose and everything to gain.