TweetWheel is another entrant in this space and it lets you find out who all amongst friends of a Twitter user know each other in common.  All you need to do is enter the Twitter user name and TweetWheel does the rest.

The application is hosted on Google Apps Engine and is relatively slow.  I only have 9 friends on Twitter still I kept getting a message stating that Twitter is responding slowly.  I can imagine what will happen to Robert Scoble if he uses this tool.  Twitter can be slow and non-responsive at times but I think it is Google Apps Engine which is the culprit in case of TweetWheel.

Coming to the visualization, TweetWheel displays all the friends in the form of a wheel and you can hover on friend’s name to see who all are they connected with.  This application can be very useful for getting to know and introduced to people who your friends connect with just like Linkedin which shows how are you connected with a person; but, for that a lot of enhancements still need to be made to TweetWheel.