I like to use music as background noise when I write. Hearing words just messes with my head, which means I have to rely on instrumentals or foreign songs. Sometimes I like to loop a single pop tune until it becomes meaningless noise. Lately, I've tried something new: a different album for each short story. The "Hanna" original motion picture soundtrack worked wonders for this weird crime story I wrote. After that, I had to piece together a "Fright Night" remake soundtrack, since the studio never released one themselves.
The "white noise" stuff (instrumentals, etc.) definitely helps me focus on my work. The Hanna soundtrack, which is all by one artist, had the perfect atmosphere: creepy, playful, surreal. It helped get me in the right mindset. Fight Night was your standard random movie songs, and I think it might have hurt more than helped. Each song was different enough to draw my attention, and by the time I managed to wrap up the story, I dreaded listening to the opening of "Bad Bad Love." No offense, Alexander. ;)