Moodle

Moodle (abbreviation for Modular Object-Oriented Dynamic Learning Environment) is afree source e-learning software platform, also known as a Course Management System,Learning Management System, or Virtual Learning Environment (VLE). Moodle is a software package for producing Internet-based courses and web sites. It is a global development project designed to support a social constructionist framework of education. Moodle is provided freely as Open Source software (under the GNU General Public License). Basically this means Moodle is copyrighted, but that you have additional freedoms.
FEATURES

Communication tools
Student Collaboration
Student/teacher Interaction
Online Learning
Discussion Board
Assessment Tools
Blogs
Databse Activities
Surveys
Peer Assessment
Event Management
Chats
Glossaries
Quizzes
Wikis
Resource Module
Forum Module
Polls/Choice Module
Course Management
User Management
Mobile Application Development
Multi Language Support
Content Mangement