JSON, SOAP, XML
Added on February 4th, 2011

Geonames

Geonames
GeoNames is integrating geographical data such as names of places in various languages, elevation, population and others from various sources. All lat/long coordinates are in WGS84 (World Geodetic System 1984). Users may manually edit, correct and add new names using a user friendly wiki interface.
More information: http://www.geonames.org/export/ws-overview.html