Not every story I work on gets its own soundtrack, but a lot of them do. My Nanovels* both have soundtracks-in-progress; one is every song about superheroes I can find, the other is a lot of songs about faith and desire.
A few years ago I participated in the CD exchange they do on the Nanowrimo forums. I sent a CD full of my favorite mashups** to my recipients. I got some excellent CDs in return, everything from J-pop to movie scores, all intended to be music to write to.
I’m not sure what approach I like better when it comes to story soundtracks: music to encourage creativity and focus, or songs that capture the mood of the story. I’ve done both. Sometimes I also fire up Coffeetivity or Rainymood. Y’know. It depends.
Do you like music when you write? Do you prefer with lyrics or without? Do you put together playlists for mood or just have something for background noise?
*Eep, I’m writing two. Eep.
**I love mashups. Like, ridiculously so.