The GP2X is an handheld running Linux. It has 2 arm-processors and a few peripherial interfaces: Available on the ext-port is a serial port which normally is used as a debugging port. Other hardware can be connected to it too, though.
http://spritesmods.com/?art=gp2xgps
Getting a superdrive into a cube is probably one of the "Holy Grail" quests for many cube owners
http://www.macmod.com/content/view/27/2/
Dr. Bob took it to the next level by adding another processor to his cube.
http://www.macmod.com/content/view/121/2/
80mm Panasonic Panaflo Fan Installation
http://www.macmod.com/content/view/23/2/