Gaurav Manek has put together a great project mixing several technologies. He has a radio controlled car interfaced with an Arduino and this can be controlled from an iPad or using a Kinect. He has given some details on how he achieved this including some source code for anybody that wants to have a go. Go to http://www.gauravmanek.com/blog/?p=33 to see it in action. The first half of the clip is for the iPad the second is for the Kinect.