Open Source projects for .NET

1 ) Mono Open Source Project

Mono provides the necessary software to develop and run .NET client and server applications on Linux, Solaris, Mac OS X, Windows, and Unix. Sponsored by Novell (http://www.novell.com), the Mono open source project has an active and enthusiastic contributing community and is positioned to become the leading choice for development of Linux applications.
Features
* Multi-platform
* Based on the ECMA/ISO standards
* Can run .NET, Java, Python and more.
* Open Source, Free Software.
* Commercially supported.
* Comprehensive technology coverage.