CIA World Fact Book -- http://www.cia.gov/library/publications/the-world-factbook/index.html -- Facts about the countries of the world, including maps and statistics.
Fedstats: Fast Facts -- http://www.fedstats.gov/fast.html -- Statistical sources from the federal government, including the Statistical Abstract of the United States and sources on health and education in the U.S.
Statistical Resources on the Web -- http://www.lib.umich.edu/govdocs/stats.html -- Government Documents Librarian at the University of Michigan, Grace York, has compiled local, state, national, and international statistics in a handy table, arranged by topic.
The Stock Market -- http://library.thinkquest.org/3088/stockmarket/introduction.html -- A great online tutorial that explains the stock market in regular language.
U.S. Gazetteer -- http://www.census.gov/cgi-bin/gazetteer -- Type in a place and state, or type in a zip code, and access the U.S. Census Bureau's statistics on that area.