YouOS – A Web Operating System
YouOS is a web operating system that lets you run diverse applications within a web browser. Small applications like sticky notes or clocks. Large applications like word processing, mp3 players, and instant messaging. Even better, it’s very easy to tweak an existing application or write your own.
YouOS strives to bring the web and traditional operating systems together to form a shared virtual computer.
On a similar note check out eyeOS