Barbara Turner vs. Georgia in 2006, that was a heck of a game. There was still time left (maybe a second) but Turner hit a crazy three to push UCONN ahead.
I also know in 2008 Maya hit a last minute bucket to beat DePaul. I don't know if it was a buzzer beater or not though.
For all of her antics, I can't recall DT ever having a game winning buzzer beater or game winner in the last 10-20 seconds of a game, although I could be wrong.