There are also deal-a-day sites that reward the buyer for purchasing a reward and then convincing their friends to buy that same reward. Don't you wish you could link up with your online friends to get deals for free? Well this is the place to do it! Add a comment with the name of the deal site, what you purchased, and your unique link. Then hopefully a virtual friend will help you out!
"Me + 3 Friends = Free"
You buy the deal and then share a unique link with your friends. Once three of your friends buy the deal through your link, you are refunded the deal cost.
When I signed up for DoodleDeals in May of 2011, I received a $20 credit. It appears that it was from Diapers.com. It expired after 30 days (and unfortunately I did not remember to use it!).