Canvas and WebGl are new (by my standards) technologies that allow javascript developers to make some pretty serious artwork in a browser without the need to use a plug-in or force the end-user to install any extra code on their systems.
As much as I'd rather plagarize javascript instead of writing it, I have a healthy appreciation for well-written code. It just happens that this example by German artist/coder Matthias Hurrle is so mesmerizing that I just couldn't look away. He has turned this combination of technologies into pure art.
See also: Matthias Hurrle Slider Gallery