This is a little project I wanted to do since I got my Radio Shack 3x3x3 LED cube project.
Basically it's a three-position-long snake that travels randomly throughout the matrix. It goes up, down, left and right, never doubling back on itself (nor does it do angles....maybe a 2.0, though pull requests always welcome!). The table loops in
loop() were copied pretty much verbatim from the RSLED_CUBE project.
In case you happened to make one of these before RadioShack went to the great bit bucket in the sky, here's another project you can run on your Arduino for fun.
There's a video on YouTube that shows this project in motion.