The daughterboard is certainly not "mystical". The photos below are for the first version. I need to respin it to fit on the production revB base board (with the double height joystick) connectors. I'm just waiting to see if there are any last issues with the design. I have a licensed copy of Chris' USB stack running.
I did an LCD daughterboard with touch screen just for fun (no plans to make a commercial version though).