The geonames.org geographical database is available for download free of charge under a creative commons attribution license. It contains over eight million geographical names and consists of 6.3 million unique features whereof 2.2 million populated places and 1.8 million alternate names. All features are categorized into one out of nine feature classes and further subcategorized into one out of 645 feature codes. (more statistics ...).
The data is accessible free of charge through a number of webservices and a daily database export. Geonames.org is already serving up to over 3 million web service requests per day.
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.
TODO
This is a large dataset and there are a whole bunch of specially exported subsets of data at which it might be worth turning into separate datasets (or at least listing here in Resources).
Linked Data
Geonames locations are available as linked data, see dataset:geonames-semantic-web
