History Education 

National Council for History Education (NCHE)

Organization of American Historians Teaching History

AHA Resources for Teachers

National History Day

History Firsthand: Primary Source Research in Elementary School

Using Primary Sources on the Web

Academic Earth Free Online History Lectures and Courses

U.S. History 

American Social History Project

History Matters: US Survey Course on the Web

The Gilder Lehrman Institute of American History

Pennsylvania History 

ExplorePAHistory.com