Links to the various agencies and departments that make up the U.S. Government. From the Department of Agriculture to Veteran's Affairs, they're all here.
http://www.infoctr.edu/fwl/

• Agency for Health Care Policy and Research (AHCPR)
  
  http://www.ahcpr.gov/
• Agency for International Development (USAID)
  
  http://www.info.usaid.gov/
• Animal, Plant and Health Inspection Service (APHIS)
  
  http://www.aphis.usda.gov/
• Arms Control and Disarmament Agency (ACDA)
  
  http://www.acda.gov/
• Bureau of Alcohol, Tobacco and Firearms (ATF)
  
  http://www.atf.treas.gov/
• Bureau of Diplomatic Security
  
  http://www.heroes.net/
• Bureau of Indian Affairs
  
  http://www.doi.gov/bureau-indian-affairs.html
• Bureau of Land Management (BLM)
  
  http://www.blm.gov/
• Bureau of Prisons (BOP)
  
  http://www.bop.gov/
• Bureau of Reclamation
  
  http://www.usbr.gov/main/
• Bureau of Transportation Statistics (BTS)
  
  http://www.bts.gov/
• Census Bureau
  
  http://www.census.gov/
• Centers for Disease Control and Prevention (CDC)
  
  http://www.cdc.gov/
• Central Intelligence Agency (CIA)
  
  http://www.cia.gov/
  
  • C.I.A. World Fact Book
    
    http://www.cia.gov/cia/publications/factbook/
• Commodity Futures Trading Commission (CFTC)
  
  http://www.cftc.gov/
• Consumer Information Center (CIC)
  
  http://www.pueblo.gsa.gov/
• Consumer Product Safety Commission
  
  http://cpsc.gov/
• Copyright Office
  
  http://lcweb.loc.gov/copyright/
• Customs Service
  
  http://www.customs.treas.gov/
• Defense Advanced Research Projects Agency (DARPA)
  
  http://www.arpa.mil/
• Defense Information Systems Agency
  
  http://www.itsi.disa.mil/
• Defense Logistics Agency (DLA)
  
  http://www.dla.mil/
• Defense Nuclear Facilities Safety Board
  
  http://www.dnfsb.gov/
• Drug Enforcement Administration (DEA)
  
  http://www.usdoj.gov/dea/
• Environmental Protection Agency (EPA)
  
  http://www.epa.gov/
  • Center for Environmental Information and Statistics
    
    http://www.epa.gov/ceis/
• Equal Employment Opportunity Commission (EEOC)
  
  http://www.eeoc.gov/
• Export-Import Bank
  
  http://www.exim.gov/
• Farm Services Agency
  
  http://www.fsa.usda.gov/
• Federal Aviation Administration (FAA)
  
  http://www.faa.gov/
  
  • FAA Technical Center
    
    http://www.tc.faa.gov/
• Federal Bureau of Investigation (FBI)
  
  http://www.fbi.gov/
  
  • National Computer Crime Squad (NCCS)
    
    http://www.fbi.gov/programs/compcrim.htm
• Federal Deposit Insurance Corporation (FDIC)
  
  http://www.fdic.gov/
• Federal Election Commission (FEC)
  
  http://www.fec.gov/
• Federal Emergency Management Agency (FEMA)
  
  http://www.fema.gov/
• Federal Office of Child Support Enforcement (OCSE)
  
  http://www.acf.dhhs.gov/ACFPrograms/CSE/
• Federal Reserve Board
  
  http://www.bog.frb.fed.us/
• Federal Trade Commission (FTC)
  
  http://www.ftc.gov/
• Fish and Wildlife Service
  
  http://www.fws.gov/
• Food and Drug Administration (FDA)
  
  http://www.fda.gov/
• Forest Service
  
  http://www.fs.fed.us/
• General Service Administration (GSA)
  
  http://www.gsa.gov/
• Geological Survey (USGS)
  
  http://www.usgs.gov/
• Government Printing Office (GPO)
  
  http://www.access.gpo.gov/su_docs/
• Health Care Financing Administration (HCFA)
  
  http://www.hcfa.gov/
• Health and Human Services
  
  http://www.os.dhhs.gov/
• High Energy Physics Information Center
  
  http://www.hep.net/
• Indian Health Service (IHS)
  
  http://www.tucson.ihs.gov/
• Information Infrastructure Task Force (IITF)
  
  http://iitf.doc.gov/
• Immigration and Naturalization Service (INS)
  
  http://www.usdoj.gov/ins/
• Information Agency (USIA)
  
  http://www.usia.gov/
• Internal Revenue Service (IRS)
  
  http://www.irs.ustreas.gov/
• International Trade Administration
  
  http://www.ita.doc.gov/
• International Trade Commission (ITC)
  
  http://www.usitc.gov/
• Marshal's Service
  
  http://www.usdoj.gov/marshals/
• National Aeronautics and Space Administration (NASA)
  
  http://www.nasa.gov/NASA_homepage.html/
  
  • Ames Research Center
    
    http://www.arc.nasa.gov/
    
    • Pioneer Missions
      
      http://spaceprojects.arc.nasa.gov/ Space_Projects/ pioneer/PNhome.html
  • Earth Observatory
    
    http://earthobservatory.nasa.gov/
  • Goddard Space Flight Center
    
    http://www.gsfc.nasa.gov/
  • Human Spaceflight
    
    http://spaceflight.nasa.gov/
  • Image eXchange (NIX)
    
    http://nix.nasa.gov/
  • Jet Propulsion Laboratory
    
    http://www.jpl.nasa.gov/
    
    • Mars Pathfinder Mission
      
      http://mpfwww.jpl.nasa.gov/
    • Stardust Mission
      
      http://stardust.jpl.nasa.gov/
    • Voyager Missions
      
      http://vraptor.jpl.nasa.gov/
  • Johnson Space Center
    
    http://www.jsc.nasa.gov/
  • Kennedy Space Center
    
    http://www.ksc.nasa.gov/
• National Archives and Records Administration (NARA)
  
  http://www.nara.gov/
• National Center for Atmospheric Research
  
  http://www.ucar.edu/
• National Credit Union Administration (NCUA)
  
  http://www.ncua.gov/
• National Endowment for the Arts
  
  http://arts.endow.gov/
• National Endowment for the Humanities
  
  http://www.neh.fed.us/
• National Energy Research Supercomputer Center
  
  http://www.nersc.gov/
• National Imagery and Mapping Agency (NIMA)
  
  Formerly known as the Defense Mapping Agency (DMA).
  http://www.nima.mil/
• National Institutes of Health (NIH)
  
  http://www.nih.gov/
• National Institute of Standards and Technology
  
  http://www.nist.gov/welcome.html
• National Library of Medicine (NLM)
  
  http://www.nlm.nih.gov/
• National Marine Fisheries Service (NMFS)
  
  http://kingfish.ssp.nmfs.gov/
• National Oceanic and Atmospheric Administration (NOAA)
  
  http://www.noaa.gov/
  
  • National Climatic Data Center
    
    http://www.ncdc.noaa.gov/
  • National Data Buoy Center
    
    http://seaboard.ndbc.noaa.gov/
• National Parks Service
  
  http://www.nps.gov/
• National Performance Review
  
  http://www.npr.gov/
• Natural Resources Conservation Service
  
  http://www.ncg.nrcs.usda.gov/
• National Science Foundation
  
  http://www.nsf.gov/
• National Security Agency (NSA)
  
  http://www.nsa.gov/
• National Telecommunications and Information Administration (NTIA)
  
  http://www.ntia.doc.gov/
• National Transportation Safety Board (NTSB)
  
  http://www.ntsb.gov/
• Nuclear Regulatory Commission (NRC)
  
  http://www.nrc.gov/
• Office of Surface Mining, Reclamation and Enforcement (OSMRE)
  
  http://www.osmre.gov/astart2.htm
• Occupational Safety and Health Administration (OSHA)
  
  http://www.osha.gov/
• Panama Canal Commission
  
  http://www.pananet.com/
• Patent & Trademark Office
  
  http://www.uspto.gov/
• Pension Benefit Guaranty Corporation
  
  http://www.pbgc.gov/
• Postal Service
  
  http://www.usps.gov/
• Presidential Advisory Commission on Gulf War Veterans Illnesses
  
  http://www.gwvi.gov/
• Railroad Retirement Board
  
  http://www.rrb.gov/
• Substance Abuse and Mental Health Services Administration (SAMHSA)
  
  http://www.samhsa.gov/
• Secret Service
  
  http://www.ustreas.gov/treasury/bureaus/usss/usss.html
• Securities and Exchange Commission (SEC)
  
  http://www.sec.gov/
• Selective Service System (SSS)
  
  http://www.sss.gov/
• Sentencing Commission
  
  http://www.ussc.gov/
• Small Business Administration (SBA)
  
  http://www.sbaonline.sba.gov/
• Social Security Administration (SSA)
  
  http://www.ssa.gov/SSA_Home.html
• Tennessee Valley Authority (TVA)
  
  http://www.tva.gov/
• Trade Representative (USTR)
  
  http://www.ustr.gov/

    See also :

• The White House
  
• U.S. Congress
  
• U.S. Federal Departments
  
• U.S. Military
  
• U.S. Government Laboratories