For those of us who remember JavaScript as a toy, only used for superfluous "DHTML", it's amazing to see it used as a real language -- capable of running an x86 emulator. If nothing else, people will have to stop pointing at Gmail as an example of an impressive client-side web application.

I have no intention of using it, but this will make it much easier to test more browsers in a single environment.

Too many Firefox extensions I can't live without now; I'd be using Opera otherwise.