They used the Makey Makey controller to turn a cupcake into a game controller! Marvin's touch exposed an issue with resistance, cupcakes, and the Makey Makey. The Makey Makey is awesome hardware, and I have mine pre-ordered.
Eric is also the author of Glow Doodle, an application I originally saw on Lifehacker. Along with Singing Fingers, which I put on my iPhone and my work iPad, these apps make interesting use of video and sound. Glow Doodle works particularly well with light spray bottles. I found a great Instructable.
I learned of an animating version of Glow Doodle on the project's blog. I prefer this version because it saves to the local hard drive instead of the Internet.