Meet Seek N’ Sneak 2: an Arduino-powered robot that can grab and move objects. It has two driving wheels that are powered using independent motors. It uses two side mounted IR proximity meter for 2D orientation while a third IR proximity meter is used to detect objects. The arm is run by 3 super-strong servo-motors. It can push up to 3 lbs.
This Arduino Mega 2560 powered robot is open sourced. It can find objects on the ground and chase other robots. More information is available here.