I present to you the fastest and easier robotic project to build with the Arduino, this ROVER consists only of a Sharp GP2Y0A21YK distance measuring sensor, a Pololu Dual Serial SMC01A motor controller and two DC motors with their respective GEAR BOX.
More info here Arduino HN - EV: Arduino Robot - ArBot 01, and in spanish here ¿Cómo apostar en ESPORT con Linux Maya 🛠?.