God bless Pandora radio. Have you tried creating a station? It doesn't do so well with score composers, though I have a combination going of Yann Tiersen, Philip Glass, and Yo-Yo Ma that's not half bad. If you do it by band - or better yet, by song - it really shines. I use different stations depending on which story I'm working on at the moment.
If I'm working on something more of a fantasy bent, I'm a big fan of film scores. Right now I've got the scores to Stardust, The Pillars of the Earth, The Tudors in a playlist, and a YouTube window open (because I can't find the cd anywhere) with the theme to the old Merlin miniseries (the one with Sam Neill).
If I'm working on something more modern, I've been rather obsessed with Mumford & Sons and Florence and the Machine lately.