Open Source Educational Software

http://gcompris.net - edu software 4 small children in 40 languages.
http://tux4kids.com
http://samhart.com/tux4kids
http://sugarlabs.org - The Software that made the One Laptop Per Child X0-1 interesting. Now a stand alone project.
http://edubuntu.org
http://curriki.org - Open Source Curriculum repository and Community.
http://moodle.org - Open Source Learning Management System (LMS)