I can't stand the shouting they've been using for the "theme" since, AFAICR, season II of CSI - but the original theme was excellent:
http://www.metacafe.com/watch/331326/csi_theme_the_original_csi_theme_song/

Has anyone found it outside the show itself? I've browsed all of John Keane's CSI score releases I could find and, sadly, this theme wasn't on any of them...