Congress
House of Representatives, http://www.house.gov
Senate, http://www.senate.gov
Library of Congress, http://www.loc.gov
THOMAS, Legislative and related information from the U.S. Congress, http://thomas.loc.gov/home/thomas2.html
Members of the House of Representatives and The Senate, http://bioguide.congress.gov

White House
General Information,  http://www.whitehouse.gov

Departments
Commerce, http://www.doc.gov
Defense, http://www.defenselink.mil
Education, http://www.ed.gov
Justice, http://www.usdoj.gov
State, http://www.state.gov
   International Information Programs (former USIA), http://usinfo.state.gov
   Digital Diplomacy
      for Students, http://www.state.gov/www/digital_diplomacy/index.html
   Foreign Service Officer
      Employment Information, http://www.state.gov/www/careers/rfscontents.html
   Office of the Historian, http://www.state.gov/www/about_state/history
Treasury, http://www.ustreas.gov

Agencies
Agency for International Development (USAID), http://www.info.usaid.gov
Central Intelligence Agency (CIA), http://www.odci.gov/cia
Environmental Protection Agency, http://www.epa.gov
Export-Import Bank, http://www.exim.gov
Federal Bureau of Investigation, http://www.fbi.gov
Federal Election Commission, http://www.fec.gov
National Aeronautics and Space Administration, http://www.nasa.gov
National Science Foundation, http://www.nsf.gov
Securities and Exchange Commission, http://www.sec.gov
Smithsonian Institution, http://www.si.edu
U.S. Arms Control & Disarmament Agency, http://www.acda.gov
U.S. Census Bureau, http://www.census.gov

U.S. Embassies Worldwide, http://www.state.gov/www/regions_missions.html

Electronic Journals, http://usinfo.state.gov/journals/journals.htm