Climatic Extremes and Weather Events: historical and current.
Disasters and Emergencies: lists of federally declared disasters from the Federal Emergency Management Agency.
Extreme Weather Sourcebook: economic and other societal impacts related to hurricanes, floods, tornadoes, lightning, and other U.S. weather phenomena.
Wildland Fire Statistics: from the National Interagency Fire Center.
Natural Hazard Statistics: information on fatalities, injuries and damages caused by weather related hazards from the National Weather Service. 1995-
Natural Hazards Data: earthquake, tsunami and volcano data.

Religion

American Religion Data Archive: Interactive maps and reports of U.S. church membership for states, counties and metropolitan areas. Also includes other surveys.

Science & Technology

National Science Foundation: statistics on R & D funding, science and technology funding, education, employment and work force including state profiles.

Small Business

Small Business Administration: national, state and local statistics on small business finances, performance and activity, small business owners and employees.
Small Business State Profiles: "baseline statistics on each state's small business economy - number of firms, small business income, industrial composition, job growth and data on minority and women-owned businesses." PDF only.

Social Issues

HIV/AIDs

HIV/AIDS surveillance report: tabular and graphic information about U.S. AIDS and HIV case reports, including data by state, metropolitan statistical area, mode of exposure to HIV, sex, race/ethnicity, age group, vital status, and case definition category. Published Semi-annually.
UNAIDs HIV/AIDS Information and Data: Includes global HIV/AIDS surveillance by country.

Social Security and Social Welfare

Green Book
Social Security Administration: Data by subject, date or type.

Taxation

Internal Revenue Service: statistics compiled from tax and information returns.

Transportation and Travel

Bureau of Transportation Statistics: general travel and transportation statistics, airline on-time statistics and other airline statistics including airline finances, transportation indicators, FAA Statistical Handbook of Aviation and transportation-related geospatial data. Comprehensive site.
Government Transportation Financial Statistics: interactive access to federal, state and local government transportation revenues and expenditures. 1977-present.
Highway Statistics: Annual publication. Fuel use and taxation, vehicle registration by type of vehicle, driver licensing, highway financing, road lengths and usage.
National Aviation Safety Data Analysis Center: access to Aviation Safety Reporting System (ASRS), FAA Accident /Incident Data System (AIDS) (incidents since 1978), Near Midair Collision System (NMACS) and the World Aircraft Accident Summary (WAAS).
National Highway Traffic Safety Administration: Traffic Safety, Fatal Accident and Crash Statistics.
National Transit Library: financial, operating, safety, performance and mileage data for mass transit agencies.
Office of Safety Analysis: railroad safety information including accidents and incidents, inspections and highway-rail crossing data.
TransStats: data from multiple agencies, a searchable index of more than 100 transportation-related databases, selective data download, interactive analytical and mapping tools.

Veterans

Veterans Administration: social and economic information about veterans, demographic and geographic veteran information, statistical information by veteran program areas and veteran survey information.

Women

Genderstats: interactive database from the World Bank. Country demographic, labor and education statistics.
The World's Women: Annual U.N. publication.