Every now and then, I'll listen to a song and think, 'wow, there's a great story here.'
One thing I love is when I hear a song and think, 'Wow! This is just the emotion that I wanted for my character. This is exactly what I wanted to say.' I make note of the songs that make me think like this and form them into the soundtrack for that story. Then, whenever I feel like I'm running dry or I've lost the emotion of the story, I put on the music and let it flow back to me.
This is one place I know I'm not alone. One friend of mine actually has a slot in her notebook labeled Soundtrack with a list of all the music that's helped shape the story. Stephanie Meyer's acknowledgments include the names of bands who inspired her during her writing.
I think music can inspire whole scenes and dialogue. I heard one song -- an internal monologue -- that turned itself into a conversation between one character and her brother.
They will probably never sell the soundtracks of books in a store, but I think a lot of stories have them. For The Thief Book (placeholder title, I swear) I've found inspiration in "Stars" from Les Miserables, "Who Am I?" also Les Miserables, "Both Sides of a Coin" from The Mystery of Edwin Drood, and "You'll Be in My Heart" from Tarzan. (It occurs to as I think about this that a startling percentage of what I listen to is soundtracks and cast recordings.)
Do you use music in your writing? What songs or bands have you found particularly influential?