OpenGroupware.org is a set of applications for contact, appointment, project, and content management. It is comparable to Exchange and SharePoint. It is accessible using Web interfaces or using local clients via WebDAV, GroupDAV, and CalDAV. Custom applications can be developed using the XML-RPC API. OpenGroupware.org runs on almost every GNU/Linux system.
Information regarding Project Releases and Project Resources. Note that the information here is a quote from Freecode.com page, and the downloads themselves may not be hosted on OSDN.