The Sparky Robot Controller package lets you control a robot using Skype. The essentials:

• MakeBoard Controller from http://www.makingthings.com/ OR iRobot Create
• Mac Mini with OSX 10.4 for the robot
• beginner knowledge of Terminal command line utility for Make Controller Version

Make sure to check the Wiki to get started: http://code.google.com/p/sparkyrobotcontroller/w/list