I built a robot on a Roomba base a few months ago. My granddaughter has named him Keith.
It is driven by a RaspBerry Pi with a Wifi dongle, and a powered USB hub.
It is powered by a Powergen mobile phone charger, which also powers the hub.
It uses an Arduino as the USB interface.
The frame is similar to the Turtlebot, but is home made.
It has a PS3 Eye camera and microphone, to give it voice commands and to stream video data as it moves.
It has speakers and voice ouptut.
It carries a Maplin robot arm, and both the arm and robot can be controlled by keyboard or voice.
It can carry an Android table to telepresence applications.
I am teaching it to fetch beer.