So I'm about to upgrade my car stereo and I was going to get one of those new cd players that can play music in mp3 format off a CD-R but then I discovered the Music Keg [
link] and oh boy did I get excited. So now I can have a player in the dash for mp3/CD-R and this harddrive full of tunes in the back. I bet you can hack it and put in a larger harddrive too, kind of like what people do with their tivos.