This is our version of the OpenServo open-source servo controller board from Sparkfun ROB-09014. It's meant to replace the existing controller board in any standard servo (~19.8mm servo width such as the Futaba S3003). With this board you can control a servo entirely with I2C/TWI commands rather than PWM, meaning that multiple OpenServos can be controlled with just two lines! The OpenServo firmware also offers some interesting control features, such as querying a servo with an unknown position, setting control gain discretely and on-the-fly, and even querying the destination of the actuator before it reaches it!