Mono

//=== http://www.mono-project.com/FAQ:_General
The Mono project implements various technologies developed by Microsoft that have now been submitted to the ECMA for standardization.

Mono is sponsored by Novell

Mono is the word for 'monkey' in Spanish.

Mono sparked/triggered C#-based components/Lib:
GTK#
#ZipLib
OpenGL's C# version -> Tao Framework
Mono.Cairo
Mono.Posix
Mono.Remoting
Mono.Http
Mono.Security
Mono.Math
Mono.XML
...

C#-related specs:
C# http://www.ecma-international.org/publications/standards/Ecma-334.htm
CLI http://www.ecma-international.org/publications/standards/Ecma-335.htm


//=== Companies using Mono
* Novell ZENworks
* MicroInvest (http://www.microinvest.net/en): is the biggest software providers for warehouse management applications in Bulgaria. Warehouse Open is warehouse management software written in C# and licensed under GPLv2...

* MindTouch (http://www.mindtouch.com/)