The High Power H-Bridge Motor Shield for Arduino is equipped with built-in current sensing utilizing the ACS712, and is capable of driving any DC motor up to 15Amp.

Download the codes here Arduino simple shield potentiometer code: Arduino shield rc car: Arduino nano module L298P code: ...

An interesting Arduino project has been published to the Instructables website showing how an Arduino CNC shield and controller has been used to create an awesome 3 axis Arduino CNC plotter.

The Chrono-tomic Arduino shield uses a C-MAX radio to demodulate the WWVB signal, demodulating it and passing it along to a PIC16F1824 microcontroller.