RockBox for iPod

is a firmware replacement for many mp3 players, including the iRiver and iPod (even the latest iPod Video).
It adds much functionality, especially in terms of file formats that can be played.
The RockBox team built upon the success of the

Note that RockBox requires an iPod formatted for FAT32, not HFS.

Rockbox has themes; one person has designed a theme that
mirrors like the iPod native interface.
did a review of the Rockbox recently.

Here is a brief quote from the (slightly outdate – doesn’t mention iPod yet) manual:

Open Source jukebox firmware for the Archos Jukebox 5000, 6000, Studio, Recorder, Recorder V2 and FM Recorder MP3 players

Rockbox is a replacement firmware for the
Jukebox Studio, Recorder and Ondio players made by Archos. It is a complete
rewrite of the software used to make the Jukeboxes play and record music, and
contains many features and enhancements not available in the original firmware
supplied by the manufacturer. Among the things that Rockbox has to offer are
the following:

  • Faster loading than the Archos firmware
  • Uninterrupted playing of MP3 files – skipping is very rare
  • More control over how your music is played
  • Built in viewers for several common file types
  • Sophisticated plugin system that allows the Jukebox to run games, a calendar, a clock, and many other applications.
  • Totally removable. (Removal of Rockbox before returning the Jukebox for repair under warranty is advised.)
  • Optional voice user interface for complete control without looking at the screen.

Rockbox is a complete from scratch rewrite of the Jukebox software and uses no
fragments of the original firmware. Not only is it free to use, it’s also released under
the GNU public license, which means that it will always remain free to both use
and to change

There is a
available, as well as
tips for using the iPod with Rockbox
(what button does what, etc).

It was mentioned in
this Slashdot comment,
which piqued my curiosity.