Here's a couple if ideas:
1. Make up some sort of ID badge/card. This could be worn around the neck in a plastic sleeve and would not be as lame as some stick-on name tag. This sleeve would also be a handy place to hold your ticket for the game. Also, it would be easy to remove and put back on and should be easy enough to wear under most weather conditions.
2. Invest in a Polaroid camera and O-maners could have their pictures taken and they would write their names across the bottom. These pictures could be posted on a board that could be displayed outside OF1. Then, all a person would have to do is look on the board and see if they recognize anyone at the tailgate.