Ebates and similar rebate sites plug into online stores' affiliate marketing systems. Affiliate marketing systems were originally developed to reward webmasters who referred viewers who frequent their websites to webstores that sell related goods. For example ... if you have a site about champion poodles, you might refer your readers to books on Amazon.com or pet food on PetFoodDirect.com by placing special links on your website. Amazon and PetFoodDirect will pay you a 10% commission on any purchases made by people that clicked on your link.

Clever rebate-hounds figured out how to game the system early on by signing up as an affiliate and then clicking on their links and earning a rebate for themselves. Some of these folks decided it would be a good idea to systematize the process and created sites like Ebates.com that aggregate all of these affiliate/rebate offers in one spot. As a shopper all you have to do is to remember to log into Ebates before you shop and click on their special link to enter the store. Somewhat suprising, the online stores are willing to play ball as Ebates shoppers are generally more loyal than random internet shoppers.

Long story short ... Ebates has almost 800 merchant partners with whom shoppers can earn rebates. Usually these rebates can be combined with coupons and other kick-backs (like rebates for using an Amazon.com credit card), so they are very attractive. It usually takes 30-60 days after the purchase date before you can cash out a given rebate (many online stores will only pay Ebates after your return period has expired) and Ebates typically holds onto the funds until you you ask them to cut you a check.

So, is there downside? Only one small one. Ebates will typically keep 1/3 of whatever commission the online store pays. So if PetFoodDirect pays a 9% commission, Ebates will keep 3% and pass the remaining 6% onto to you. This means that, if there are online stores where you buy hundreds or thousands of dollars per year, you should consider signing up for their affiliate program directly so you can get the full 9%. If you infrequently shop at a store, it's probably easier to have Ebates do all of the work and keep their 1/3. Also, Ebates will frequently go out and negotiate a better rate than the average affiliate could get. For online stores where you do a large amount of shopping, the way to compare is to find the link on the store's website to become an affiliate. It may say right there how much affiliates get paid or you may have to "officially" sign up at their third party affiliate provider ( usually either Linkshare and Commission Junction ). Anyway -- it's not worth it unless you spend a ton of money at a given store.