The iRobot create is a mobile robot platform that can be controlled by uploading various scripts to determine which actions it will take. As it has a simple DB25 interface socket and uses serial communication, Matt Gray and Golan Levin have documented a method to control the iRobot with an Arduino. This includes uploading and executing a command script to the iRobot.
When developing your own Arduino-embedded projects, consider the Freetronics LeoStick:
Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo which can be used a knock sensor and various tune and sound effects. For more information and to order, click here.