XM/mod library and player.
sverx has released version 1.00 of libXM7 XM replay library (used in the very good Anguna homebrew game) and a demo player built using it called xm7Play XM/MOD Player.
For the unaware XM is a format similar to MOD but somewhat more advanced. While it intended for use in games the xm format has also found considerable use in chiptunes.
The library is designed to work on the ARM7 leaving you with the ARM9 to run games.
A great deal of information on the libraries and theory behind XM is available on this page.
