I have been working on some gameboy advance related projects, here are some toys:
womb-0.3.1 is a linux kernel module for the dumb multiboot cable designed by Ajo at GBA Multiboot Inteligent Cable. The kernel module turns out to be less reliable compared to the dos version, even though it should have full control of the machine during transfer (more research required :). The module needs devfs, and has so far only been used with kernel 2.4.x.
Womb started life as a direct dos port of Ajo's dmb, this version seems to be more reliable on the machines I have tested it on. (if you are using a win32 system, you may need a tool such as winzip to extract .tar.gz files).
fairy-0.2.18 is a little test screen I wrote to play with the sprite registers.