I remember the Wendy's AirTran coupons on the drink cups. This was 2005. On a windy day the tossed away cups would accumulate in the back of the parking lot and I got a couple of free flights out of it. 34 cup coupons for a free one-way (or close to it).

In the very first days of Coke Rewards you could get Hilton points, no limit. Scored a bunch, asked friends to save their caps/codes. Limits on rewards/redemptions soon followed.