I've seen the FM modulated changers.
It's basically a wired remote and fm modulator that you connect to a normal changer.
I've got the modulator from a JVC one, and it sounded quite nice..
(I didn't get the full kit, just the modulator, as I needed it to connect my computer to a stereo that had no line in's.. =)

Also, if you put an antenna on the modulator, it can broadcast quite well. We used it for a party in my student house, with 6 stereos in various rooms playing mp3's from my computer.. =)