Maps

Geographic Names Information System
Contains "information about physical and cultural geographic of all types in the United States, associated areas, and Antarctica, current and historical, but not including roads and highways."

Getty Thesaurus of Geographic Names
Contains nearly 1 million place names representing approximately 900,000 places, with their latitudes, longitudes, and political and physical hierarchies.

Mapquest
Directions and maps for customized travel within the U.S.

Xpeditions Atlas
Black and white maps of country or region of the world in either gif or pdf formats for printing and copying

See also the Maps homepage of the Public Documents and Maps web site.