Use this search to determine who two or three tweeps follow in common.  This is the killer search if you want to understand a social graph.  

* Enter the names of three senior people at a given company and you not only get the names of almost everyone (with a Twitter account) who works with them, but you can see who the smallest player is who has their ear.
* Enter three experts' names and you can see who they all rely on for news and information.
* If you're looking to recruit within a given company, mapping the cross section of tweeps followed by three people in that company uncovers lots of additional players, some of whom have lots of influence.