I did some programming work on an interactive installation for the Vancouver Mini Maker Faire this year (2011).
The project was a collaboration between Tangible Interaction, Chairman Ting, and myself.
We had kids in mind when we thought about creating the install, so we used a heat sensor mounted 4-5 meters high and tracked body movement around a grid of characters.
Each character had a personality (sound, light, face) and would light up when the kids got close.
It was great to see the kids faces and excitement when they saw what was happening!