Drupal is an open source content management platform powering millions of websites and applications. It's built, used, and supported by an active and diverse community of people around the world.
http://drupal.org/

Joomla is one of the world' s most popular open source CMS (content management system). With millions of websites running on Joomla, the software is used by individuals, small & medium-sized businesses, and large organizations worldwide to easily create & build a variety of websites & web-enabled applications.
http://www.joomla.org/

ReadyGo's e-Learning software makes it easy for us to create courses that employees enjoy and that meet their managers expectations"
http://www.readygo.com/

Liferay delivers open source enterprise solutions for portals, publishing, content, and collaboration.
http://www.liferay.com/

CourseLab is a powerful, yet easy-to-use, e-learning authoring tool that offers programming-free WYSIWYG environment for creating high-quality interactive e-learning content which can be published on the Internet, Learning Management Systems (LMS), CD-ROMS and other devices. And a fully functional version is offered for FREE!
http://www.courselab.com/

BigBlueButton is an open source web conferencing system built on over fourteen open source components to create an integrated solution that runs on mac, unix, or PC computers. In the true sense of open source, we invite you to try out and participate in our project.
http://www.bigbluebutton.org/

Moodle is a Course Management System (CMS), also known as a Learning Management System (LMS) or a Virtual Learning Environment (VLE). It is a Free web application that educators can use to create effective online learning sites.

The Sakai Collaboration and Learning Environment is a free and open source Courseware Management System. It features a set of software tools designed to help instructors, researchers and students collaborate online in support of their work--whether it be course instruction, research or general project collaboration.

WizIQ offers a rich set of intuitive tools for online teaching courses live and online in the Virtual Classroom, and is a complete solution for student teachers and organization, fully integrated with moodle and other LMS.

Red5 is an Open Source Flash Server written in Java that supports:

• Streaming Video (FLV, F4V, MP4, 3GP)
• Streaming Audio (MP3, F4A, M4A, AAC)
• Recording Client Streams (FLV and AVC+AAC in FLV container)
• Shared Objects
• Live Stream Publishing
• Remoting
• Protocols: RTMP, RTMPT, RTMPS, and RTMPE

SharePoint's multi-purpose platform allows for managing and provisioning of intranet portals, extranets and websites, document management and file management, collaboration spaces, social networking tools, enterprise search, business intelligence tooling, process/information integration, and third-party developed solutions. SharePoint can also be used as a web application development platform

Document Management, Web Content Management, version control, Records Management, Image Management, Activity workflow Advanced search and indexing, Desktop integration with Microsoft Office, OpenOffice.org and, Pluggable authentication: NTLM, LDAP, Kerberos, CAS, Multiple Database support: MySQL, PostgreSQL, Oracle Database, IBM DB2, Microsoft SQL Server (Enterprise Edition).

Is a free open source course authoring tool that support building e-courses and export the result to HTML, Scorm , .exe fully integrated with LMS like Moodle and others.

Is a free open source course authoring tool that support building e-courses and export the result to HTML, Scorm , .exe fully integrated with LMS like Moodle and others.

openSIS is a web-based Open Source Student Information System, a great deal of required functionality and appears to be easy to use based on the online demo website. openSIS is developed and maintained by Open Solutions for Education OS4ED.