OPENLY LICENSED REPOSITORIES*
http://www.opentextbook.org
http://cnx.org
http://collegeopentextbooks.org/opentextbookcontent/open-textbooks-by-subject
http://globaltext.terry.uga.edu/books
http://www.theorangegrove.org/open_textbooks.asp
http://apple.com/education/itunes-u
http://www.khanacademy.org
http://oyc.yale.edu
http://ocw.mit.edu/courses
http://see.stanford.edu/see/courses.aspx
http://ocw.usu.edu
http://ocw.nd.edu
http://academicearth.org
http://www.merlot.org/merlot/index.htm
http://www.nsdl.org
http://amser.org/index.php?P=BrowseResources
http://www.doaj.org

http://www.cosmolearning.com
http://www.learnerstv.com
http://www.humbox.ac.uk
http://www.nap.edu
http://www.teachingchannel.org
http://mathdl.maa.org/mathDL
http://www.nobelprize.org
http://textbooksfree.org
http://www.freetechbooks.com
http://www.youtube.com/education

*Although many resources are openly licensed, some are not. The license status is generally indicated for each resource.