I've always just used this http://www.adafruit.com/products/954 http://www.adafruit.com/products/954 and connect to the pi via serial. Although with the 0 it

I've always just used this http://www.adafruit.com/products/954 http://www.adafruit.com/products/954 and connect to the pi via serial. Although with the 0 it would require soldering on 2-4 pins.