Converter is based heavily on Ladyada's original "USB NeXT Keyboard with Arduino Micro" tutorial (http://learn.adafruit.com/usb-next-keyboard-with-arduino-micro/overview). If you build this converter, show Adafruit some love and do it using an Arduino Micro (http://www.adafruit.com/products/1315) or their ATmega 32u4 Breakout Board (http://www.adafruit.com/products/296). Arduino Micro should work fine using the Arduino Pro Micro configuration above, same pins numbers and everything.