This was an experiment to discover how complicated it would be to write an iPod simulator that actually plays music. Result: not too bad!
It uses the Audio library of the device it is running from (therefore won't run properly in a simulator) and uses actual UIKit table views configured to emulate the iPod interface. Also, the click wheel accepts rotary inputs just like the real thing.
There are several unimplemented features, and many screens are blank when they are opened through navigation. But the basic music playback for artists, albums, and tracks is all there. It also includes an animated “Now Playing” screen that imitates the “marquee” txt labels used by the iPod UI.
Unfortunately Apps that emulate an iPod are vetoed by Apple (guess how many people must have tried that already), so this won't be in the App Store any time soon...