Calais
The Calais Module integrates a Drupal site with the Thomson Reuters' Calais web service, which "automatically creates rich semantic metadata for the content you submit" using natural language processing. I.e., you feed it plain text, it gives you semantic markup.
Calais is Thomson Reuters’ Semantic Web Service that enables publishers to automatically metatag the people, places, facts and events in their content to increase its search accessibility on the Web.