Someone else mentioned something I'd like to echo, but in no particular order:
1. Aaron Boone's home run. I was a die-hard Yankees fan at the time in Boston, so it was incredibly satisfying.
2. First ND game was against Michigan in 2002. I had no idea who anyone was...I barely knew that the coach was Ty Willingham (I was in fifth grade and never grew up with football being a big part of my sports life). But my grandpa took me to the game, and the rest is history. That's why I'm posting here now. (ND won 25-23, and if my memory is correct, students rushed the field).
3. I'm a big soccer fan. Not one particular game sticks out, but I've seen Messi for Argentina twice against the U.S. (this past March and in June, 2008). In the first game, I'd say seeing him warm up alone was worth the admission fee alone. I've been fortunate enough to be at Ronaldinho's first game on tour with Barcelona back in '04 or '05 (?)...against Juventus in Foxboro, MA. Saw Ruud van Nistelrooy score a brilliant volley against Juventus at a separate game, etc. First soccer game I ever went to, I was 7 and it was at St. James' Park...Newcastle United/Aston Villa. Alan Shearer was sent off after 30 minutes, but I still idolize him. Enough soccer. You get the point.
4. Sun Bowl, 2010. Beat Miami, sums it up.
5. Blue Gold game, 2007. Too many details to tell, but that was the best day of my life, bar none. Best experience ever.
I'll leave it at that. I think I've strayed away from the topic of memories, but I couldn't help myself. Forgive me. I got a bit over-excited.