Mine has to be a Mets-Phillies game in Philadelphia I saw a few years ago. The Mets did lose, but Mike Piazza, my favorite player, hit a home run in the game. I beleive it was Piazza's last year with the Mets.
Another good one I saw was a Rutgers-South Florida College Basketball game I saw at the RAC. With about 20 seconds to go, RU was down 2 with the last possesion. It was a shame that they almost, but didn't quite, hit the game winning three. Still a competitive and exciting game, though.
So I repeat-what is the most memorable professional or college sports game that you have ever been to?