The A-Star (A*) product line from Pololu are very compact microcontoler plateform. A-Star are modules that can be programmed via their micro USB plug (like Arduino does) and have GPIOs, PWM output and analog input as any other microcontroler. The A* are preloaded with an Arduino Compatible bootloader.
Pololu A-Star, Atmel ATMega32U4, micro-USB, bootloader compatible Arduino
A-Star 32U4 LV Robot Controller with Raspberry-Pi Bridge
motor controler for robotic project