Open Groupware
http://www.opengroupware.org
A set of applications for contact, appointment, project, and content management comparable to Exchange and
SharePoint portal servers. Accessible using
WebInterfaces and various native clients, including
MicrosoftOutlook. Its servers run on almost any GNU/Linux system, can synchronize with Palm PDAs, and are completely scriptable using XML-RPC.
Based on the
SoPe application server (a free
WebObjects replacement).