The following web sites are helpful for teaching history:
American Memory (Library of Congress)
http://memory.loc.gov/ammem/index.html
Digital History
http://www.digitalhistory.uh.edu/
Documents Library
http://teachingamericanhistory.org/library/
Great Speeches
http://www.historyplace.com/speeches/previous.htm
History Matters! (George Mason University) http://www.historymatters.gmu.edu/
Our Documents (National Archives)
http://www.ourdocuments.gov/
Understanding by Design
http://ubdexchange.org/
U.S. History Quiz
http://quizhub.com/quiz/f-history.cfm
Southern Labor Archives - Georgia State University Library
http://www.library.gsu.edu/spcoll/pages/pages.asp?ldID=105&guideID=510&ID=4223
Foundations of U.S. History
http://chnm.gmu.edu/loudountah/index.html