Hosted by the U.S. Census. Also a good source for data about agriculture, education, employment, health, law, etc. Their website features valuable links to other official statistical resources, both domestic and international. A great place to find information on internet access in the US, including how many people have a computer and what kind of internet subscription service they use.

(Cornell University) - A search interface to the Roper Center for Public Opinion Research, a non-profit education and research organization that studies politics, government, public institutions, international relations, business, social affairs, and consumer behavior. Includes sources from major broadcasting and news organizations.

A nonpartisan organization providing social science data and public opinion polling results on global issues.