The Yahoo! Internet Location Platform provides a resource for managing all geo-permanent named places on Earth...In simple terms, the Service allows you to look up the unique identifier - called the Where on Earth ID, or WOEID - for almost any named place on the Earth; it also allows you to resolve a WOEID you have received from a third party - such as Fire Eagle™ or Upcoming - to the place it represents.
Yahoo Developer Network [developer.yahoo.com]

Sounds interesting, although I can't get it to return any results at the moment.