Wubuntu
Found via Digg:
Wubuntu is supposedly a web version of the popular operating system Ubuntu (which, by the way, I highly recommend as a Linux distribution). It’s actually just some very clever JavaScript, but it’s done so well that I thought it deserved a mention. Also, if such a polished result can be achieved by a lone coder working in their spare time, just think what a team of professionals could do if they worked really hard on creating a great web application that was sufficiently similar to a real desktop that most users couldn’t tell the difference. I think such a situation is still some way off, but things do seem to be moving in that direction.