Best online summary of HTML5 & related features

http://apirocks.com/html5/html5.html What a boon to find it summed up so nicely and organized in such a  straightforward way.

Learn HTML5/Canvas procedural drawing

If you want a very quick hands-on tutorial on how to create a simple [extensible+procedural] drawing app in HTML5, check out Harmony. [Here's the author's abstract]

You can download the page source and play with it locally. Which is a huge plus.