I was first alerted to Mr. Tweet through a tweet from @leeoden. Mr. Tweet is a service that finds influential people that you should be following. All you need to do is follow @mrtweet and the service will generate a report of influencers outside of your network based on your existing network and interactions. The service also provides a report of current followers that you should be following back (somewhat similar to FriendorFollow). Once the report is generated Mr. Tweet will send you a direct message with the link to the report.
The "Influencers in my network" report ranks the influencers from most important to least important. They show you the top Followers for each person as well as how often they post Tweets. The report provides a Following-to-Follower ratio. This ratio provides some insight into how influential the person is (the higher the ratio the more influential). There is also a link to the Google search results for each person. I like this feature because it provides some additional insight into who the person is and how they relate to your network.