I built a custom circuit around an ATMega168 w/Arduino bootloader.  It came out great and made it on to a few blogs!  I used my circuit to control Adafruit’s Game of Life kit, which was embedded into a hoodie (I didn’t use her PCB, just her chip). Check out the circuit with rollover info —

completed GoL + EKG Hoodie circuit

First Wear!

Read more about the project on my personal blog.