Open Content Sources 

Content Repositories

• Exemplary Collection of Open eLearning Content Repositories
• OER Recommender  
• 80 Open Education Resource (OER) Tools for Publishing and Development Initiatives 
• OER Commons
• MERLOT
• Connexions
• Internet Archive
• FREE: Federal Resources for Educational Excellence
• COL Knowledge Finder
• Creative Commons
• OpenDOAR
• Curriki
• Hippocampus
• Edu2.0

Books

• Project Gutenberg
• Open Textbooks
• Read Print
• Bartleby
• Online Books
• Electronic Text Service
• Open Book Project
• World Digital Library 
• The Assayer 
• Internet Public Library 
• Bartleby
• Textbook Revolution
• eBooks and eTexts 
• LeMill  
• Wowio 
• WikiBooks
• Scholarship of the California Digital Library
• MIT textbooks
• Hofstra University Hofprints-Hofstra University E-Print Archive
• Cornell Race, Ethnicity, and Religion Project
• Digital Assets Repository

Primary Sources

• Primary Source Learning Handbook
• Use of Primary Sources in Library of Congress  
• National Archives Lesson Plans
• Library of Congress
• Use of Primary Sources
  • Primary Source Learning
  • Using digitized primary source materials in the classroom

Open Courseware

• Open Courseware Consortium
• OpenCourseWare Finder Finder
• Wikiversity

Sources of Images and Sound

• United States Federal Government Photo Repositories
  • U.S. Government Graphics and Photos
  • Department of State Portraits and Stock Photographs
  • National Park Service Digital Image Archives
  • Fish and Wildlife Service Digital Library System
  • Federal Emergency Management Administration Photo Library
  • U.S. Geological Survey Photographic Library
  • Bureau of Land Management Digital Photo Library
  • National Aeronautics & Space Administration Ames Imaging Library
  • National Aeronautics & Space Administration Video Gallery
  • National Oceanic and Atmospheric Administration Photo Library
  • Department of Agriculture On Line Photography Center
  • Library of Congress Prints & Photographs Reading Room
  • National Science Foundation Image Library
  • Department of Defense Multimedia Library
  • U.S. Mint Image Library
  • Customs and Border Protection Image Library
  • U.S. Goverment Photos and Multimedia  
• Photos at Flickr Licensed under Creative Commons
• BurningWell
• Subject Specific Images for Educational Use from University of Michigan 
• OurMedia Learning Center
• Behold
• Librivox
• Open Photos