Yup... Well here's my submittion, a fireworks simulator. It's basically a particle system set up to imitate firework-like explosions. Spawn rate is based on frame rate. It fits Canada Day too.
It's coded in Java, and packed into an Windows executable file, so you'll only need the JRE to run it, not the SDK.
Yeah... I was on a very tight schedule. Heh, still worth checking out. Wanted to submit something this year.