Library of Congress Resources - http://www.loc.gov/
American Treasures of the Library of Congress - http://lcweb.loc.gov/exhibits/treasures/
A Document History of Social Justice - http://www.sojust.net/
Valley of the Shadows, Civil War - http://valley.vcdh.virginia.edu/
National Geographic - http://nationalgeographic.com/
National Digital Library - http://memory.loc.gov/ammem/ammemhome.html
Berkeley Digital Library - http://sunsite.berkeley.edu/Collections/
Duke University Special Digital Collections - http://scriptorium.lib.duke.edu/
Today in History - http://memory.loc.gov/ammem/today/today.html
Chronology of American Historical Documents - http://www.law.ou.edu/hist/
Archiving Early America - http://earlyamerica.com/
Historical Advertisements - http://scriptorium.lib.duke.edu/adaccess/
NARA The Digital Classroom - http://www.archives.gov/digital_classroom/index.html
NASA Educator Resource Center - http://www.cotf.edu/erc/main.html
Native American Women - http://photoswest.org/exhib/gallery4/leadin.htm
Panoramic Photographs - http://memory.loc.gov/ammem/ndlpedu/collections/pphoto/history.html