If it's too loud, you're too old, @Chopper
I've got a playlist burned on to my Xbox for every map and the music choices progress in intensity as the rounds do and really adds to the effect and feeling of the intensity that starts to pile on while playing Zombies. A lot of it is actually just soundtrack stuff from other games/movies that really fit the environment of the map. For example, I start off my Moon playlist with a couple tracks from the Dead Space soundtrack. And my SNN playlist starts with this sort of eerie Asian music haha. Then to finish it all off, each playlist ends with the maps actual EE song.
If I can dig one up, I'd be happy to share.
EDIT:
I'm not sure how you guys do it, but I just create a playlist via iTunes, then burn the playlist on to a blank disc and rip it onto my Xbox. Here's my SNN playlist. If you decide to give it a go, let me know how it worked for you!