Mambo - http://www.mamboserver.com/
A content management system. Features include article
ranking, online editor, web-based administrative interface, simple
template engine, etc. [Open source, GPL]
Forge - http://www.mamboforge.net/
A development and distribution environment for the
community to further expand the Mambo project. The site is used to host
components, templates, plug-ins, modules and anything related to Mambo
[Open Source, GPL, commercial use prohibited].
Hut - http://www.mambohut.com/
Provids templates for the Mambo CMS.
Mamboportal - http://www.mamboportal.com/
News and file repository for Mambo CMS.