Progress

Here are the designs for the cards I am making.

The first I call "Input" which has some protection for the 15V inputs for the Concept Card. This will be the hardest to make as it is two sided and may be difficult to line up. I haven't made this yet.
The next image is "Switch" which takes the 5v from the sanguino and switches it to 15V and also takes the 15v status signal from the concept and knocks it down to 5V. I made this last night, and it turned out pretty good.
On both these cards I tried to keep the power rails on the outside and signal wires in the middle. Hopefully they will be pretty robust from a noise perspective.
The picture on the previous post was "Output" which takes the output from the Concept Card and interfaces to the IGBT's.

I also need to make a 10-15V input to 15V output regulated power supply for up to 20 amps, but this can wait for now as I have an old mac power supply kluged with a 7815 dangling from my desk.

If anyone is wondering, I'm using the free version of Eagle 5.6 for layout, and the reason I did three cards is I am limited to 2.5 by 3.5 inches on the PCB because that is all that will fit through the epson printer in the CD tray.