I'm a sucker for any film which has at least one bit of excellent music in it, or at least some moments where the music syncs up astoundingly well with the action/editing. Not just licensed music, but proper scores too.
So I'm going to share some of my fabourite ones here, and probably add more later, Feel free to put suggestions in the comments too.

1. Scott Pilgrim vs. The World -Clash at Demonhead

The movie may be an acquired taste, but this is still my favourite moment from the film. Cheating a bit, this is the full version not heard in the film itself. And yes, that is the actress herself singing, possibly better than the original cover they have on the official soundtrack.

2. Drive- Kavinsky (feat. Loveboxx) 'Nightcall'

Opening credits are one of those things where you really have to hook an audience so why not use a neon cityscape, a fast car and this playing loud?

3. Drive- College & Electric Youth 'A Real Hero'

What, who says I can't have two from the same picture? Sounds incredibly retro Eighties in the best of ways, and used to score a montage of the main character on his first day out with his attractive neighbour. Trust me, it's a thing of beauty.