Ken Moss, former head of Microsoft's search unit has build up ‘CrowdEye,’ a real-time Twitter search engine that aims to allow users to better mine Twitter to get a pulse on hot topics. The service in public beta offers up not only the latest tweets on a topic, but also a list of the most popular links on a topic and a tag cloud of associated terms. Among its features, CrowdEye has a historical view that allows one to see how the discussion on a topic has evolved. Although, for now, that historical period is only three days. For example, users can see how many Tweets mentioned "Obama" or "Tehran" or "Apple" during a certain time period. When a story breaks on Twitter, Moss said that people can track who was on top of the story first.
More info: CrowdEye