Some really cool demos were presented at the HTML5 Community Night event at Microsoft on April 26th 2011. Here are a smattering of the links to the demos.
Cross-platform multi-player games built using HTML5. Supports browsers as well as iPhone and Android.
PowWow: A HTML5-based multiplayer game showing off WebSockets and WebGL.
SVG Girl: a Japanese anime “video” implemented completely in SVG!
CSS3 GRID SYSTEM
IE9’s Grid System in CSS.
There were many other demos but these were the URLs that I managed to snag during the presentation. Will update my post if I find links to the other demos.