Social Source Commons

Enables educational institutions to build vibrant online communities and improve information flow.

Online community for social change similar to YouTube.

Free E-Advocacy for Grassroots

Collaboration platform for groups. Combines the features of discussion forums, email lists, calendars and social networks. Groupsites can be configured to be public, semi-public, or private and secure.

The Community Kit for SharePoint is a set of best practices, templates, Web Parts, tools, and source code that enables practically anyone to create a community website based on SharePoint technology for practically any group of people with a common interest.

Core to the Toolkit is a role-playing game that teaches face-to-face organizing for residents and community leaders. Developed by the Center for Third World Organizing. Learn to knock on doors!

Hosted solution for event and conference management. Includes a calendar of conference events.

dotCommunity is a powerful web-based application suite for the development of online communities.

GoingOn hosts your social network for free in exchange for letting them serve ads on your site.

New York City News and Policy, and online news paper.

Joomla is an award-winning content management system (CMS), which enables you to build Web sites and powerful online applications. Many aspects, including its ease-of-use and extensibility, have made Joomla the most popular Web site software available. Best of all, Joomla is an open source solution that is freely available to everyone.

Hosted community blogging service.

Social networking for readers of blogs

MyTopix is a discussion forum poised to compete with some of the other players in the bulletin board market. It has all the features you need to get a community up and started quick and nothing that you don't.

OpenPlans is a free, hosted, and integrated suite of web-based tools with wikis, email lists and more coming soon. It is built on top of Plone, but is fully hosted and lets group create their own projects with no need to install a CMS

Piczo allows its users to create fully customizable personal websites that do not require any understanding of html code.

Plumi is a free software video sharing platform based on Plone.

RT is an enterprise-grade ticketing system which enables a group of people to intelligently and efficiently manage tasks, issues, and requests submitted by a community of users.

Second Life is a 3-D virtual world entirely built and owned by its residents.

TikiWiki CMS/Groupware is a full-featured, web-based, multilingual, tightly integrated, all-in-one Wiki+CMS+Groupware, Free Source Software (GNU/LGPL), using PHP, ADOdb, Zend Framework, jQuery and Smarty. It is actively developed by a very large international community and is translated in over 30 languages. TikiWiki can be used to create all sorts of Web applications, sites, portals, knowledge base, intranets, and extranets.

TikiWiki offers a very large number of features "out-of-the-box", arguably more than any other Open Source Web Application. Highly configurable & modular, all the features are optional and administered via a web-based interface.

Major features include a robust wiki engine, news articles, discussion forums, newsletters, blogs, a file/image gallery, bug & issue tracker (form generator), a links directory, polls/surveys and quizzes, a FAQ, a banner management system, a calendar, maps, Mobile Tiki (PDA, VoiceXML and WAP access), RSS feeds, a category system, tags, an advanced themeing engine (Smarty), a spreadsheet, live support, Shoutbox, inter-user messages, a menu generator, an advanced user, group and permission system, internal search engine, external authentication support, and much much more.

Open Source Content Managment System

Integrated discussion boards, chat and e-mail lists for full-featured communities

XOOPS Cube is a a free Open Source Web Application Platform released under BSD license and Base Legacy modules released under GPL license: user and groups management, message, search, forums, social news, rss, gallery, blog, flat data and contact forms and much more plug-ins.

The XOOPS Cube Project is friendly managed, maintained, developed and supported by a volunteer group to expand your network, vision, creativity and skills.

Zanby is a free individual and group organizing platform. Individuals and organizations can start or join unlimited groups, use a robust events management system, upload documents and photos, manage group members, and more.