From digging through my bookmarks, I found this site. I remember looking into doing something with this about 4 years ago, but never got around to messing with it (I moved about 1000 miles away a month or two after looking this up, and so never got to try any of it out.).
MP3 Mobile - HOWTO
Now, since this article's a few years old (5?), I'm sure there's a whole lot more you can do with it, but it's a starting place.
daBum