Hmmm for me It's a mix of 'sweet dreams" from the 'Sucker Punch' soundtrack, and "cloud Atlas" extended theme.
For me, those two songs are so bang on. The Sucker Punch song for when I am writing something exciting of fast paced, or writing in a character playing on the edge with their own life, its punchy and risky, dangerous... and then I switch down into the cloud atlas part to write the more human parts, the sensitive bits where people feel things.
I don't think I could write half as well as I do without music, and it is music that helps me stay focused on my story rather then anything else actually going on around me.