To underline the point that JavaScript is really growing (along with HTML5) and going to change a few things, I wanted to point out to this cute JavaScript Christmas Tree, by Roman Cortes. (Thanks to @JimMcKeeth for the hint.)
The Christmas Tree is visible at http://js1k.com/2010-xmas/demo/856 (it is in a frame, but I felt it would have been unfair to embed it here). Notice you basically need the Chrome browser to see it properly and fast. No Internet Explorer, AFAICT. THis demo was submitted to a contest of less than 1KB JavaScript demos, but it is way better than all others I've seen.
Roman wrote a very nice blog post with graphical information (more than words) showing how he built this demo. Very nice, although I'm not such a graphic person. You can read it at http://www.romancortes.com/blog/how-i-did-the-1kb-christmas-tree/.
Since I felt I wanted something for this post and some of you might have troubles seeing the demo in their browsers, I though of making a short video and hope the author of the demo is OK with it: