additional semantic for existing information sources

how information enrichment works in real world showing two public use-cases based on different technologies:

• freebase
  "Freebase is an open, shared database that contains structured information on millions of topics in hundreds of categories. This information is compiled from open datasets like Wikipedia, MusicBrainz, the Securities and Exchange Commission, and the CIA World Fact Book, as well as contributions from our user community."
  
  this means that applications like freebase using already existing information and trying to add additional semantic to them based on combining and extracting information and context or in this case let user add additional semantics without modification to the source of the information.
  
  the tool thinkbase using freebase to provide a visual graph of information and corresponding link dependencies.
  
• MailMark using a xml database (Mark Logic) as backbone for building the application just on XQuery
  
  the semantic comes from information aggregation and combination. in this application no additional user interaction is possible
  

both examples are very useful and showing real world application which you might transform into your own information landscape.....