I've been listening to Radio Rivendell for about a year or two now, and it's my favorite station to have on in the background when I'm writing, working on games, or whatever else. Essentially, it's all music from fantasy/historical films and a LOT of game soundtracks.
With no commercials and a lot of material from amateur and new composers (mostly guys messing around with digital keyboards of varying quality), they've got two pluses in my book. I'd be remiss if I didn't plug them, so here's a banner link. Check it out!