The history of American taxation. Check out the tax returns filed by Bill Clinton, Franklin Roosevelt, and other past presidents.
IRS: Dirty Dozen Tax Scams (.PDF)
Legal and illegalt tax tactics.
MSNBC: Government Tax Refund Database
Does a state and/or the IRS owe you money? Type your name into this database and see.
Cool stats with taxes.
This portal to Census 2000 data is an easy-to-use tool for investigating U.S. demographic trends. Developed by the Social Science Data Analysis Network (SSDAN) at the of Michigan it produces graphics and exportable trend data.
This site has collected and analyzed data from numerous sources to create profiles of all U.S. cities. It featuresthousands of pictures, maps, satellite photos, stats about residents (race, income, ancestries, education, employment…), geographical data, crime data, housing, businesses, political contributions, weather, hospitals, schools, libraries, houses, airports, radio and TV stations, zip codes, area codes, user-submitted facts, similar cities list.
Social Security Calculator
Use this online tool to estimate what your Social Security income would be a particular age.