No plug-ins. No Flash. Just an HTML5 port of the Quake II game engine.

Apparently some folks at Google decided to use their extra time in a very, very productive way:

We started with the existing Jake2 Java port of the Quake II engine, then used the Google Web Toolkit (along with WebGL, WebSockets, and a lot of refactoring) to cross-compile it into Javascript. You can see the results in the video above — we were honestly a bit surprised when we saw it pushing over 30 frames per second on our laptops (your mileage may vary)!

Result? Utterly wonderful. [Google Web Toolkit Blog via TechCrunch]