Do people really compile soundtracks for their novels? I've never thought about this too much. I do sometimes listen to music when I'm writing but I tune it out so I might as well not be listening to it at all.
But if your Nano novel were made into a movie (completely faithful to your story, of course) and there was a soundtrack for it, what would it be? I think mine would be completely orchestral with a very dark, gothic feel. But not overwrought! I don't have angst as a major theme. And whenever something scary or dramatic shows up, there would be really harsh and dissonant incidental music--like Psycho.