Wow, a lot of my favorites have already been mentioned. Gonna have to dig deep here. How about...
ALL THAT JAZZ - Sure, I suppose it's hokey in a way, but I've always loved the whole sequence with Roy Scheider & Ben Vereen doing Bye Bye Love as the main character lies dying.
CHARIOTS OF FIRE - Forget the overplayed theme, it's the scene where Eric Lidell throws his head back in pure bliss and the synths swell for ten seconds or so that music really works for me.
DAZED AND CONFUSED - The opening seconds where the car creeps through the parking lot while blasting Sweet Emotion. That's what it's like to feel cool in high school.
GLORY - The final siege.
MILLER'S CROSSING - All of it, but I'll single out Danny Boy playing while Leo is under attack.
CARPENTER'S THE THING - Pick any scene with just the music in it.
TEZUKA'S METROPOLIS - Ray Charles singing I Can't Stop Loving You as the city collapses in ruins.
and just to throw something really weird out there...
PHANTASM - The scene where Jody & Reg sit on the porch and work on their song. In the midst of all the surrealism this scene really anchors the characters into real and likable individuals for me. I like the song too