I have been building a Quadcopter. So far, I've been running the Aeroquad software after a few failed attempts to do my own.
But! Now that I know the frame works and that I am capable of flying the damned thing, it's back to custom software for me -- which was the whole point from the beginning. To that end, I have written some simple Arduino test code for the various components of my system:
In case these are useful to anyone other than me.