<a href="http://www.geocities.com/zrizez/" target="_blank" >rize_foa </a> has released an Extended Palette demo for the Nintendo DS, heres what he says about it:

This is a demo primarily for extended palettes. However I also included a number of other things such as 4 scrolling backgrounds, button presses, hardware timers and alpha blending. Also closing the lid shuts down the screens and 2D cores. It's heavily commented so it could serve as a good tutorial for a n00b as well.

Unfortunately it only runs on real hardware at the moment.

Download here --> http://nintendo-ds.dcemu.co.uk/extendedpallette.shtml