Squishy circuits are circuits made from conductive playdough! It's a fabulous way of allowing young kids to safely create circuits with a material they are familiar with. I met Matt Schmidtbauer of the Squishy Circuits Store at a conference in October and took home their$25 kit of LEDs, motors, and buzzers. I just finished a tutorial on how to connect the elements of the kit to Hummingbird, so for your next project consider making up a batch of conductive dough, sticking some LEDs in it, and controlling them via your computer through Hummingbird.
Video and written resources can be found at:http://www.hummingbirdkit.com/?q=content%2Fsquishy-circuits-tutorial