LambdaMOO Server This SourceForge project includes the latest release of the Lambda MOO server and provides unofficial patches, CVS access and similar services. http://sourceforge.net/projects/lambdamoo/

WinMOO Unofficial server that runs on Windows. http://www.stanford.edu/~cunkel/WinMOO/

EmberMUD Flexible open-source MUD engine, capable of supporting almost any role-playing setting. http://sourceforge.net/projects/embermud