Generally since I'm from the same 'hood as "America's Coach," I would say the Miracle on ice. Certainly when Mark McGuire smacked 62 I remember exactly where I was, who I was with, but to be honest between his 2001 U.S. Open route and his 1997 Masters, I go with Tiger's 1997 Masters event, which really got me crazy into golf. I know I am leaving an event or two out, but that one really stuck with me to this day.
You?
You?