Windows4all.com - online virtual operating system
Windows4all.com is a Silverlight based online virtual operating system. It is is a website that simulates an operating system inside your web browser. Windows4all.com replicates the desktop environment of a modern operating system. You can launch applications right away without installation.
Windows4all.com is web-based and requires Silverlight 2 to operate. Besides desktop, taskbar, start menu and sidebar currently it includes such applications:
Also it supports installing program functionality. But this program should be developed in Silverlight, have valid url for xap file and be available across domain boundaries.