free teaching tools - open source educational software

I'm putting together a list of open source educational software, that

*may* become part of a future projects, or to give to interns to play with.

The list, of course could be endless, so just considering things that are ready for production, a real 'market leader' or a project that shows real promise.

It's just a brain storm at the moment.  Anything obvious missing from this list?

*** LMS Tools (besides the obvious Moodle, Sakai, Canvas etc)

Chamilo     http://www.chamilo.org

Google Course Builder   https://code.google.com/p/course-builder/

*** Discipline Specific

WebWork http://webwork.maa.org (Mathematics)

*** Lecture Capture

Opencast Matterhorn http://opencast.org/matterhorn/

*** Web Conference/Collaboration

Big Blue Button http://www.bigbluebutton.org

*** Portfolio

Mahara https://mahara.org

*** Repositories

Dspace http://www.dspace.org