Guntis Kulikovskis is raising funds for SumoBoy - Arduino-based robotics kit for education and sport on Kickstarter! SumoBoy is the world's first mini sumo robotics kit that consists of two parts: a programmable fight robot & the prototyping board set.
Here is an idea for a vertical garden in a classroom (plus a fish tank). This could also work in other places -- homes, places of worship, community centres, etc. Maybe even outdoors? With a mesh covering over the fish tank, the cats couldn't get in.