Geography:
http://www.geographic.org
Maps: world, country, population, climate, etc. Various world ranking lists and flags included.
https://www.cia.gov/library/publications/the-world-factbook/index.html
Site contains current demographic information for each nation.
US History:
http://www.historyteacher.net/USQuizMainPage.htm
Helpful quizzes on American history.
http://usinfo.state.gov/usa/infousa/facts/history.htm
Site contains basic facts of American history, from pre-Colonial to Present.
World History: http://www.hyperhistory.com
Timelines, lifelines, historical maps, etc., links to History Chart.
http://www.historyworld.net
Timelines, articles, etc.
Government:
http://www.c-span.org/classroom/govt/3branches.asp
Site covers current events in the three branches of government.
http://phrontistery.info/govern.html
Site provides basic definitions for different types of governments.
http://bensguide.gpo.gov/9-12/government/branches.html
Site explains the different roles of the three branches of the federal government.
Economics:
http://www.virted.org/ECONOMICS/Econ.html
Site explains basic economic concepts and simplifies complex concepts.
http://www.bea.gov
Site covers current events in the US economy.
http://www.weforum.org/en/index.htm
Site covers current events in the world economy.