I already finished two skins for the basic menus of the M3 DS Simply. But these are just for Nuance demoscene family members. But some public ones will also surely soon see the light. Skinning is quite easy and comfortable. You just change the graphics and fiddle around with the ini file a bit and the job is done. Next challenge will be a fitting skin for moonshell. This will be a bit more tricky I guess, but not too complicated. Moonshell works quite well and plays flawlessly all files I dropped on the microSD. Also reading eBooks is quite nice. You can get free eBooks via moonbooks.net.
PS: And moonshell even plays .MOD! YAY!!!