Admit it, the first thing you thought of when you saw the 40h was the 
classic game Nibbles! 
(http://en.wikipedia.org/wiki/Nibbles_%28computer_game%29)

Well it's here, complete with explosions on impact.  I'm a novice 
programmer so please bear with the fact that:

1.  You have to give the app focus before the up/down/left/right arrows 
will be recognized.
2.  I'm providing the source (not a java app) because I wasn't up for 
writing the interface to figure out what port your 40h is attached to 
(default is COM3).  You'll have to change the monome initilization in 
setup().

All that's required is processing (http://processing.org/) and the 
monomic library (http://jklabs.net/monomic/)

You can find the pde here:

http://www.makingthenoise.com/download/nibbles.pde

The text source here:

http://www.makingthenoise.com/download/nibbles.txt

And an (unnecessarily large) video with Jega providing the soundtrack 
here:

http://www.makingthenoise.com/download/processing_nibbles.avi

Enjoy!

thank god someone finally made this. star explosion at the end is really 
a nice touch.

i suspect you have some other gems around.