I purchased two power supplies from Raidmax at Fry's Electronics, one in 2008, and another in 2009 . In both cases, there was a large ($40) rebate.
While the power supplies have worked fine, I was disappointed not to receive the rebates as expected. Both times, I had to call the company to complain 6 months after the purchase, and twice they claimed to have sent me the check many months before, but I never received it. After they remailed the payment, I received the checks I was owed.
I track my rebates in a special rebate account in Quicken, which is how I noticed those weren't missing. I have bought items with several thousand dollars worth of rebates in the last few years, mostly from Fry's. Raidmax has been the main offender on unpaid rebates, so I thought it was worth sharing my experience with them.