Government of the United States

The President
http://www.whitehouse.gov

The Presidency Project (from UC Santa Barbara)
http://www.presidency.ucsb.edu/index_docs.php
Massive online archive of presidential primary sources — Executive Orders, news conferences, State of the Union speeches, Public Papers, etc. Current documents too.

The U.S. House of Representatives
http://www.house.gov

The U.S. Senate
http://www.senate.gov

The U.S. Supreme Court
http://www.supremecourtus.gov/

Documents of the U.S. Congress
http://library.bowdoin.edu/govdocs/us/congdocs.shtml

GPO Access
http://www.gpoaccess.gov/index.html
The Government Printing Office's web site, devoted to full text congressional, executive and judicial publications with links to related web sites.

Federal Government Resources on the Web (Univ. of Michigan Library)
http://www.lib.umich.edu/govdocs/federal.html
A fine collection of web sites from and about the U.S. federal government. Scholarly, frequently updated, and well organized.

U.S.A. Services
http://www.info.gov/
An easy-to-use collection of links to practical information on consumer affairs, elections, health, taxes, passports, etc.

FedStats
http://www.fedstats.gov/
A central point for locating statistics from a variety of US agencies.