GitHub repository: skyman/nin10kit
Primary language: C++
Description: (Formerly brandontools) A set of tools for doing homebrew game development, includes look up table generators and and image to C exporter for Nintendo's Gameboy Advance, DS, and 3DS systems.  In addition the GUI version of the program allows you to see what the image would look like on a real gameboy advance before exporting.  Coming soon the ability to edit the bitmap/palette/tilemaps before exporting to the GBA.