This shield makes it easy to build an Arduino-controlled Zumo robot. The shield mounts onto an assembled Zumo chassis, connecting directly to the chassis’s battery terminals and motors, and the Arduino plugs into the shield, face down. This shield includes dual motor drivers, a buzzer for playing simple sounds and music, a user pushbutton, and a 3-axis accelerometer, compass, and gyroscope. The shield boosts the battery voltage to power the Arduino, and it breaks out the Arduino I/O lines, reset button, and user LED for convenient access and to accommodate additional sensors for things like obstacle and edge detection.
More technical information at Pololu.
This product (version 1.2) vill be discontinued and replaced with new version 1.3.