Ingame music from the comfort of your browser
If you're away from your gaming PC and need a quick fix, the official World of Warcraft website now features a music player where you can listen to many of the in-game music tracks (as well as Warcraft III and Warcraft II tracks), plus two special dramatic episodes themed for Christmas and Halloween 2004. Complete with dancing ogre, it'll keep you going until you can get back to Azeroth.
You can find the soundtrack on CD if you're especially enthusiastic, but as the CD came with pre-orders and the Collector's Edition of the game, you may need to hunt around on eBay for it.
