Almost a couple of years ago I released ChainShot, a Konfabulator Yahoo Widgets Widget. When the Google Homepage API was announced internally, a contest was held to develop sample modules in time for launch. I decided to port ChainShot, partly due to a lack of any better ideas, but also because I was curious how the two systems compared. As it turned out, my game (since renamed to ColorJunction) was selected for external release (you can find it in the directory).

If you're looking to make your own module, the documentation is pretty thorough. The sample modules all have unobfuscated source code, so they should serve as good starting points. There's a pretty powerful JavaScript API (e.g. we provide you with a proxy so you can jump across the same-domain limitation of XMLHttpRequest) and a descriptive XML language. But in the end, all your AJAX-y/HTML/CSS/JavaScript skills can be used pretty much as is (an advantage the Homepage API shares with Apple's Dashboard).

N.B. ChainShot/ColorJunction is a clone of the 80s Japanese game of the same name.