http://hackaday.com/2010/03/18/arduino-based-multiboot-cable-for-game-boy-advance/

Arduino based multiboot cable for Game Boy Advance
March 18, 2010 By Mike Szczys 20 Comments

[Steve] wanted to do some ARM development and set his sights on the Game Boy Advance as a development package.
In order to get his code onto the device he build an Arduino-based communications cable.