I'm listening to Mouse World Radio on Live365 right now, and they're playing through the entire 30-minute soundtrack to Splash Mountain. Most of the clips are shorter, but they do have a good variety so far of music from each of the parks and resort hotels:
http://www.mouseworldradio.com/
Subsonic Radio is another one I listen to, and you can even request different tracks from all the parks (and
Disneyland):
http://www.subsonicradio.com/