A project I have been considering, is a "Mobile Presence Device" for one of the remote team members on my team at work. (to cut down on travel?!?) My thought was to use an inexpensive android tablet running Skype mounted on a web controlled(via a WiFi enabled controller (Propeller?) robot base. In my case I am considering either one of the hobbyist robot bases that are available or perhaps a "re-purposed" generic robot vacuum.
Mechanically my rough design has the tablet mounted on the top of a 3-4 foot pvc pipe (or wood dowel) that is attached to the robot base, so that the Skype screen and camera are somewhere around eye level of a sitting person.
Seemed like this might be the kind of "green" project that you might want to consider for a future earth day show -- feel free to use the idea if it seems useful!