Healey-
I think that they make some of their money from the interest. Not enough to pay for the products, advertising, hosting, employees, shipping, affiliates, etc. I'm sure that most of there money comes from people who don't follow through with the rebates. Most of the items they sell are closeouts, discontinued items, etc.
Another way they could make their money is by actually receiving a rebate from the manufacturer or a "kickback" on each item they sell from the manufacturer. For instance, if they sell an item for $150. Straight off the top, theres about 2% to the credit card company. Ok, you "loan" cyber-rebate the $150 for 12-14 weeks, lets say at best they receive 6% on their money. (($150 * 6% Annually)/52 weeks) * 14 Weeks = $2.38. Ok, basically the interest pays for the credit card fees ($150x2%) = $3.00. Lets say the manufacturer has a $15 rebate and you could normally buy this item in the store for $35. Cyber-rebate then sends in the $15 rebate to the manufacturer and they get $15 back. That $15 should pay for the cost of the item. In the end, they send you your $150 back, they still have the $15 from the manufacturer's rebate that they received. All in all, you have a free product, they get their manufacturer's rebate PLUS all the people who don't fill out the rebate forms. When you multiply this by the number of items that they sell, it adds up.
Thoughts?