I'm going to give my neighbor a tank of gas. He has a snowblower and will keep my walk and driveway clean all winter. Seems like a good trade.

If you don't have someone that can use a free tank of gas, find someone pulling into the station that looks like they could use it and give a stranger an early Christmas gift. Karma points are far more valuable than airline miles in my opinion. Shouldn't let free gas go to waste.