It may very well be an old news already, but it’s so amazing I just have to share it.
Fabrice Bellard wrote a more or less full PC emulator in Javascript. And, unsurprisingly, Linux can run on it ! I’m not talking about ajax or some kind of client-server communication. Linux runs entirely in your browser, and uses the HTML 5 local storage as disk space.
I say WOW, check it for out yourself: