Here are some things I have made
Song Seeds - Automatically generate notes within a scale and play them. Evolve additional tracks which will compliment the initial seed when played together.
Cellular Automaton - Cellular Automaton made with javascript, canvas, and jquery. Initial setting is "Conway's Game of Life" rules, but you can adjust the rules.
Scale Comparison Tool - View side by side Google Maps windows which always stay in scale with each other.
Car Painter - Drive around and paint