Moodle is a course management system (CMS) - a free, Open Source software package designed using sound pedagogical principles, to help educators create effective online learning communities. You can download and use it on any computer you have handy (including webhosts), yet it can scale from a single-teacher site to a 50,000-student University. This site itself is created using Moodle, so check out the Moodle Demonstration Courses or read the latest Moodle Buzz.
Also very powerful: Claroline is an Open Source eLearning and eWorking platform allowing organizations to build effective online courses and to manage learning and collaborative activities on the web. Translated into 35 languages, Claroline has a large worldwide users’ and developers’ community.
Dokeos is an Open Source elearning and course management web application translated in 34 languages and helping more than 1.000 organisations worldwide to manage learning and collaboration activities.
TED for the rest of us.\nThe main purpose of the project Videolectures.Net is to provide free and open access of a high quality video lectures presented by distinguished scholars and scientists at the most important and prominent events like conferences, summer schools, workshops and science promotional events from many fields of Science. The portal is aimed at promoting science, exchanging ideas and fostering knowledge sharing by providing high quality didactic contents not only to a scientific community but also to a general public. All lectures, accompanying documents, information and links are systematically selected and classified through the editorial process taking into account also users' comments.
H. Luo, R. Shen, C. Niu, and C. Ullrich. Proceedings of the 14th International Conference on Artificial Intelligence and Statistics (AISTATS), 15, page 470--478. (2011)