Like many writers, I listen to music while I write. Also, I have noise-blocking headphones, which are especially useful if there are a bunch of little people around shrieking (i.e. the kids, whenever they are awake).
It took some experimentation to find the right music; some songs distracted, or interfered with flow.
I really like Pandora because you can choose the song or artists you like, and it gives you a bunch of songs similar to the one you chose. Also, I need all the help I can get; most of my music is just whatever is on the radio these days.
I started out with a song with these qualities:
pop rock qualities
a subtle use of vocal harmony
acoustic rhythm piano
intricate melodic phrasing
mixed acoustic and electric instrumentation
thru composed melodic style
major key tonality
prominent organ
acoustic rhythm guitars
romantic lyrics
I ended up with the following playlist. Each song helped open up my writing, like it was the soundtrack to my character.
I should also mention I wrote QUEEN OF SHOW in first person, because the character’s voice was so strong; next time I use varying viewpoints I’ll see if they require different music. (I did use music to write HOUSEWIFE, but I never wrote down what I listened to, and it’s so long ago that I forgot. I think it was a lot of U2.)
And I also found that if I had to think about something technical during revisions, such as why a scene wasn’t working and how to make it work, I had to turn off the music altogether. I guess I get distracted that way.
Sweet Pea by Amos Lee
New Soul by Yael Naim
When I Look to the Sky by Train
Story of a Girl by Nine Days
Fireflies by Owl City
Hang on, Little Tomato by Pink Martini
Hallelujah by Jeff Buckley
Hey Soul Sister
The Way I Am by Ingrid Michaelson
MARGARET DILLOWAY 
I love Jeff Buckley’s “Halleluja.” I can listen to it countless times. It’s actually tough for me to write with music. I get distracted easily and find myself having to turn it down. You have a good point that perhaps it’s the type of music depending on the writing. Maybe I’ll try different types and see how that works.
I know what you mean. If I’m trying to write something that’s not flowing, or worse, doing math and having trouble, I have to listen to something that has no lyrics and that I’m already very familiar with, so the parts of my mind I need for the task at hand aren’t busy following notes, melodies, turns of phrase.