Also not strictly a reward, but when Pan Am first issued its WorldCard with First USA, they included Mastercard checks (initially three) which were good for a maximum of $10,000 a piece and were miles earning. After using those three, they issued another three. Not only did these earn 1 mile per dollar spent, but IIRC if you paid your balance in full early, they accrued no interest. In essenc this was a free 60,000 miles. About 4 months into the programme these the mileage element of these checks were revoked.

I second what has been written above about the KLM miles match. I made out big time from that one.