I have read that putting music on your blog is a Cardinal Sin, but I use music every time I write. Music shapes my mood, my characters, and my dialogue. Music can set the scene and music can relieve you when you have written crap. Essentially, I'd be an entirely different writer without music. I am not sure if I'd be a better writer or not, but I can tell you that there's no going back.
Here's a song that has inspired more than one story. Without this song, I would have 14,000 fewer words under my belt.
"Weighty Ghost" Wintersleep
What songs prompt your muse to give back?