Course Management Systems
ANGEL (www.angellearning.com) is the CMS that I presently utilize to teach online.
Blackboard (www.blackboard.com/us/index.bbb) is the CMS I employed to host my classes when I first started to teach online.
Moodle (http://moodle.org) is a free open source CMS that I have used as a student in some online classes.
The EduTools website (www.edutools.info/static.jsp?pj=4&page=HOME) critically compares course management systems.