I've actualy got the mail in rebate on two Lynksys air cards. $15.00 each time.
The problem with mail in rebates is that they favour the company too often.
From experience, 80% of the time we would forget to give them out, 5% of the time the store would not have any of them to give out, 5% of the time we`d give out the wrong one, 5% of the time the customer would get tired of waiting for us to find them one and just say forget it, and of the other 15% of people, at least 2 out of 3 of them would never send them out.
From what I remember reading, only about 5-8% of people actually end up getting the rebate that they`ve centered their purchase around, because of all of the hoops involved. More $$$ for the company though.