Mono is a project led by Novell to create .NET compatible runtime, tools and utilities to develop and run .NET applications in various Operating Systems: Linux, Unix, Mac OS X, Windows, Solaris, BSD and Others.

 It has also IDE called MonoDevelop and has also many active projects like Moonlight (Microsoft's Compatible Silverlight).

 In 2006, Microsoft and Novell announced a joint agreement whereby Microsoft agreed to not sue Novell which gives a green light to Mono Project.

 Give it a look it is relay worth to try www.mono-project.com

YouOS is an amazing Web-Desktop interface that uses Javascript to communicate with remote server and make you fell like working on workstation or Operating System capable to save state.It has more than 600 applications have been developed by using YouOS API and IDE.

YouOS was chosen to be the 7th in PC World's list "The 20 Most Innovative Products of the Year" on 2006.

take it live at http://www.youos.com

Singularity is a Microsoft Research project started in 2003 to build a highly-dependable operating system which mean Kernel, Drivers and Applications written in managed code using C# and C# extra extensions.

Questions might arise in our minds: Is it possible that Microsoft will replace Windows with Singularity? What make it different from Windows? Is because it was build from scratch or have more to offer than Windows?

Any way you could try it but be careful it is classified under research and don't expect Windows like graphics.

Official home page