CostCritter - Features rebates, coupons, promotions and a cash back program for online stores. Registration required; free membership.
Ebates - E-commerce portal that connects with the most popular retailers and pays cash rebates on purchases.
Ed Foster's Gripelog: Rebate Bait - Explains how and why the rebate industry, especially on computers or electronic equipment, has (over)grown, and how rebate fulfillment shops make their money.
Rebate Report Card - Rebate rankings submitted by consumers. Rebates are ranked from A to F, depending on length of time to get the money, complexity of instructions, quality of customer service and related details.
Rebate Roulette - User-submitted rebate reviews and ratings.
Refunding Online - Devoted to the hobbies of refunding and couponing. Includes newbie tips, glossary and manufacturer directory with 1-800 numbers for most major brands.