Want to listen to the music of World of Warcraft without actually playing the game? It's possible -- anyee has posted a quick how-to over on the WoW Livejournal. The music is sitting on your computer in MPQ files, which are a proprietary Blizzard archiving format for their games. But there are a number of MPQ extractors and editors out there (the two recommended are MPQ Extractor for the Mac and MPQ Editor for Windows), so download one of those, use it to break open the MPQ you're looking for, and then find the music you want in that folder. Extract it out, and voila, you've got Warcraft music to listen to whenever you want.
I know what you're saying -- this might be against the Terms of Service. But actually, it's not -- the ToS only mentions "modifying" game files, and since you're simply extracting them from their archives, you're not actually modifying them. Plus, Blizzard actually authorizes the extraction of this music for use in noncommercial machinima, so as long as you use this music and any other assets for personal, noncommercial use, Blizzard has no problem with it. Of course, you'll be stuck listening to the music in bits and pieces designed for looping rather than a snazzy CD set. But if all you want to do is taking a listen to some of the tunes out of game, there you go.