(ProQuest) - Provides government statistics, business, trade, and research information, and private and international statistical information. U.S. government statistics go back to 1973 and private and state sources go back to 1980.
Hosted by the U.S. Census, a good source for data about agriculture, education, employment, health, law, etc. Their website features links to other official statistical resources, both domestic and international.
(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.