Html5demo is a project mainly written in JavaScript, it's free.
A quick and dirty test of HTML5
Show clearly that exponential sinusoid is way better than linear. Inpired by MacBook Pro sleeping LED.
Simplistic particle engine using canvas.
Demo of CSS3 transitions.
Example of visualisation on music using Mozilla Audio Data API.
Simplistic audio player using <audio> tags and a little bit of canvas.
Demo online at http://paul.cx/public/html5demo