Anthropology Outreach Office, Smithsonian Institution
http://www.nmnh.si.edu/anthro/outreach/outrch1.html
A wealth of teaching resources are available at this site.
American Anthropological Association
http://www.aaanet.org/committees/commissions/aec/resources.htm
This site presents a collection of links, including classroom resources.
Society for American Archaeology
http://www.saa.org/publicftp/PUBLIC/home/home.html
This site includes educational and outreach resources, the Archaeology and Public Education Newsletter, and much more. The focus is on archaeology.