The day before yesterday, I was watching a relatively crappy movie from the 70's named Driller Killer. It's from a director whose work I like, but I have to say that the only thing that really kept me watching this movie was the punk music from the band that's in the movie, which made the movie all that more interesting to me. In the same manner, there are some awesome movies that are taken to WAY awesome by their soundtracks. The obvious example for me is Blade Runner, with its haunting music created by Vangelis.
Maybe what they have in common is that their music really fits in with their visuals, but maybe there are other reasons.
What other movies can you think of which have music in them that takes them to a whole other level? Why do you feel that is?