If you were impressed by GMail, prepare for a surprise. Some very talented individuals have been creating demos that push the graphical power of Javascript and DHTML into the realm of 3D games. Of particular note are redbug (online demo, IE recommended) and neja.

Bonus: The author of neja, P01, has a brilliant technique for drawing lines, and explains it in a very lucid tutorial.

It's funny, but I'm still impressed as I watch browser-based apps pick up functions we used to think were limited to desktop software. This isn't going to stop, though, and pretty soon the web will be a platform that blends the best of client-server software and the best of desktop software. When that happens, Microsoft is going to be pissed off.