Daniele Benedettelli has been working on several new projects with the NXT lately. One of them is a robotic wheel chair with that uses the NXT. On his website he says:
"The aim is to realize a robotic wheelchair that will allow disabled people to gain mobility and independency. The motivation of this project is that existing smart wheelchairs are very expensive and they are not so smart.
The idea is to realize such a vehicle using low cost hardware such as LEGO MINDSTORMS NXT, a netbook, other off-the-shelf technology, and custom sensors."
You can watch Danny's project presentation and several other videos using this link.