Sites

Getty Thesaurus of Geographic Names (Popularity: )
http://www.getty.edu/research/tools/vocabulary/tgn/index.html
Find place and feature names worldwide with the Getty Thesaurus of Place Names. Results include coordinates as well as contextual information such as state and province.

GEOnet Names Server (Popularity: )
http://earth-info.nga.mil/gns/html/index.html
Searchable database of place names and features outside the U.S., developed by the National Imagery and Mapping Agency.

U.S. Geographic Names Information System (Popularity: )
http://geonames.usgs.gov
Find out where a city or other feature such as a mountain or lake is in the United States.

Canadian Geographical Names (Popularity: )
http://GeoNames.NRCan.gc.ca
Server queries can be made by name or point coordinates for current, historical and undersea places and geographical features.