You should look at the Bedini Motor. It claims free energy, but is an extremely efficient pulsed DC motor.
One of my friends has successfully implemented Bedini with arduino http://www.wilhoit-az.com/mark/free_energy/MAllen7424.php
I myself also use arduino for similar projects except with plasma aetheric reactors instead of a ferro-resonant aethric reactor http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1256402716