Another design wish:
It is possible brick a 328P by setting the fuse bits wrong, particularly those involving clock source (after all, the first thing you do with an AVR is to either to zero the clock prescaler fuse-bit or change to an external clock source).
It is however possible to unbrick it by either parallell programming a chip erase (section 28.7.3 in the manual) or just send a couple TTL pulses (I usually stay on the safe side with several 100s) to XTAL1 per bit data sent over SPI (28.8). I've always used the latter, as it doesn't require 12V, but on the other hand, it doesn't help when the ISP disable fuse has been set. Until today I've set the fuse-bits for clock wrong countless times, but never managed to set the ISP disable fuse.
Oh, and btw, THANKS. Now I won't have to reinvent the wheel and instead I'll order one Gert-board per R-Pi
Btw, "manual" is http://www.atmel.com/dyn/resou.....oc8271.pdf
-edit: added url