A one-evening porting here: libmikmod for fpc4nds
It is a portable sound library for playing various music modules like MOD, S3M, IT, etc.
I have tested for mod format only, so it could return crap... in case bug report me! ^_^

Hardware mixer (based on ARM7 cpu) works fine on real hardware, but on no$gba I get some distorted sound; software mixer works fine both on real hardware and no$gba, but eats more ARM9 cpu

Download here! (532 kb)