Apart from the excellent subject matter, I often pull up this site during UI/UX discussions. Amit clearly has the ability to do really advanced JavaScript visualizations, but he only uses it exactly when necessary. Most of it is a plain document like you might write in Markdown, but when he uses JavaScript, it's illuminating, connected to all the other examples, and clean. Any animation he uses is clearly initiated by the user, and is there not because it looks cool, but because the intermediate frames help the user understand what's happening. It also never moves the rest of the layout around. I go back to this site any time I'm pondering how to do good online documentation, interactive help, tutorials, or even text-heavy presentation of results.