||GBA Programming with DevKit Advance|
I have written a Photoshop plugin (Mac/Win) to convert images to header file definitions for use with GBA development systems. It supports high quality dithering, both 8x8 tiled and linear palette and true colour images, and LZSS compression. GPL release is planned.
For more information see http://www.telegraphics.com.au/sw/#gbaexport