I believe, and I have previously stated, that HTML5 is the logical successor to the likes of Flash, for providing interactive graphics within a browser.
To further HTML5's progress in taking over the world, I have put together these pages detailing how to use the HTML5 canvas element.
Much of it is a summarised version of the HTML5 specification put out by WHATWG, including extra commentary, tips and tricks that I have encountered while trying out the various properties and methods in the browsers that support it.
Additionally, I have included working examples of most of the canvas methods with commented source code at the bottom of each page.
Finally, the commented source code for Webtris, the Tetris clone I wrote using the canvas element, is provided here as well.