Groupware Tools
Sijio is an easy to use and fully customizable PHP driven FREE open source community software.
More Info 
Developer: Sijio
License: Freeware
Operating System: Not Available
epesi Business Information Manager is 100% web based open source CRM/SFA application that includes shared calendar, contacts, tasks, notes and more.
Developer: Janusz Tylek
License: MIT/X Consortium License
Operating System: multiplatform
Major features include articles, forums, newsletters, blogs, a file/image gallery, a Wiki, drawing, trackers, a directory, polls/surveys and quizzes, a FAQ, chat, a banner management system, Webmail, a calendar, maps, charts, Mobile Tiki (PDA and WAP access), RSS feeds, a category system, a theme.
Developer: tikiwiki
License: GNU Lesser General Public License (LGPL)
Operating System: OS Independent (Written in an interpreted language)
phpGroupWare is a multi-user groupware suite.
Developer: phpGroupWare
License: GNU General Public License (GPL)
Operating System: *nix, Windows
eGroupWare is a multi-user, web-based groupware suite developed on a custom set of PHP-based APIs.
Developer: eGroupWare
License: GNU General Public License (GPL)
Operating System: (UNIX, Win NT, XP, Linux
Web-based groupware written in PHP.
Developer: more.groupware Development Team
License: GNU General Public License (GPL)
Operating System: Platform Independent
A collaborative web-based system for projects and project management; WebCollab is easy to use, and encourages users to work together.
Developer: WebCollab
License: GNU General Public License (GPL)
Operating System: Platform Independent
Free software for contractors to manage their projects and tasks online.
Developer: Joe
License: GNU General Public License (GPL)
Operating System: Unix, Windows
Ceica Minus Groupware by Seich is a quick and effective platform for groupware work it is easily customizable using modules which are easily installed.
Developer: Sergio Diaz
License: GNU General Public License (GPL)
Operating System: Linux, apache, windows
Z-Push is an implementation of the ActiveSync protocol, which is used 'over-the-air' for multi platform ActiveSync devices, including Windows Mobile, Ericsson and Nokia phones.
Developer: z-push
License: GNU General Public License (GPL)
Operating System: OS Independent, POSIX