I have a ZIP file I recieved from somewhere or another with a lightly sorted lsit of every track featured in the GMT gamemodes. I am putting it on Dropbox for the sake of this list.
EDIT: While I'll still be doing this, you might want to check out this thread from the original GMT forums, wherin most or every song used was linked. Be sure to scroll past OP, because theres more than just that.
EDIT2: Yeah I've decided against uploading this. It's basically piracy. Just check those lists out.