The IBM Watson Concept Insights service allows you to discover content which may or may not be found using a traditional keyword search. The service uses a graph created using content that has been ingested from the English language Wikipedia.
The IBM Watson™ Concept Insights service provides an API that enable developers to work with concepts and identify conceptual associations in the content that you provide as input to the service. Input content is auto-tagged against a concept graph, which is a formal representation of the relationships between concepts that are present in the data on which it is based. The concept graph used by the Concept Insights service is based on content that has been ingested from the English language Wikipedia.
Read More: http://www.ibm.com/smarterplanet/us/en/ibmwatson/developercloud/doc/concept-insights/