UConn in 2000 was awesome. I think some of our more exciting mid-season games lose luster after the team falls short of expectations, but the Dome was electric that night. When DeShaun hit the consecutive threes in the first half to double up the score (40-20 or 44-22, I think), it was as loud as it's been for a weeknight game in the ten years prior and the 12 years since. Really great environment - he aisle in 103 was shoulder-to-shoulder with students until halftime and both (brand-new) baskets were torn down in the (somewhat execessive) court-storming.
I don't think anything can top the late-'80s and early-'90s Georgetown games, but Pittsburgh in 2003 and the 2000 and 1994 UConn games make for a nice honorable mention. And the 1994 upset of Arizona, though played before a small pre-Christmas crowd, was a pretty fun game, too.
Missed Villanova in 2010, unfortunately.