For everyone who loves the infinite possibilities of client-site JavaScript, and who at the same time does not love the blink-taggy smell that this kind of library evokes, I present to you the world's first distributed, web-based operating system: see https://www.urdesk.net/desk
This has been under very active development for going on 3 years now, and it is just starting to get to the point where it can stop being called a prototype or experiment.