I don't ALWAYS listen to the album Everybody Digs Bill Evans when I write, but I bet I do 50% of the time. I listen to it over and over again, then listen to it over and over and over again.
I don't really know why, other than it has a sort of Pavlovian effect on me. I now associate the opening measures with the sound of writing. This album is what writing sounds like to me. So it gets me in the mood. In fact, if I listen to it outside of the context of writing--in a car or coffeeshop or a a party--I feel the urge to write. Like some sort of drug addict.
I think this is a really good thing. For me.
Oh, and Peace Piece may be the most beautiful song ever made.