I don't own an iPod or similar player, my music collection is not large and I prefer to listen to radio. But if I need to kill time with music (e.g. during a trip), then I just use Zaurus. With Opie, it can be quite interesting:
It is just the normal Opie Media Player, with the pod skin. No need for iTunes-like or special tool on the desktop side, I just use drag-and-drop within Konqueror.
Consider that the four-way navigation buttons of the Zaurus SL 5500 serve also for the next/previous and increase/decrease volume, this nicely emulates an iPod-like player.
It can survive up to three hours. This is actually quite astonishing since the battery is already quite old. Even if it's new, it's just not up to iPod's. All songs are in CF card, there is no aggressive buffering, MP3/Ogg decoding is done in software (not special DSP chip). So, not so bad.