It seems Twitter becomes more popular every day. There are plenty of tools, here is one that I found incredibly useful because it does the job that I was doing manually. Obviously that seems to be the case with anything you would find useful, if it fits a need you use it. So here is a free, easy, tool that takes just one step.
Once you have used Twitter for a while you start to spend time looking for an following those that would be of interest to you. This can be a very time intensive process. There are many tools to use and assist you, such as http://search.twitter.com to find those talking about topics you are interested in by using keywords. Many other tools are available to track those conversations, see a list of Twitter tools.
Mr. Tweet Tool
I ran across Mr. Tweet which suggests a list of influencers that you are not following based on their own algorithm. It also creates a list of followers that are following you but you are not following them. Both of these lists are useful and they create a web page with this information generated automatically. What an easy way for you to review these two lists. All you have to do to get started is follow @mrtweet. It can take a week or two but they will send you a direct message to your twitter account with a link to the reports. Here are two screenshots of what you will find (I covered the individuals information).
Influencers I am not following
Here is a screen shot of what they provide on each individual they suggest I take a look at. They auto generated a list of 200. If you compare the statistics on this individual at the top of the influencer list with the individual at the top of the follower list below you will see the influencer has over 20,000 followers. Obviously from that one example and the others in the list there is a distinct difference between their algorithm for creating the lists.
Those who Follow me that I am not Following
Take a look at this screen shot of the list of those that follow me but I am not following. Mr Tweet auto generated a list of 127 and ranked them. They ranked them in an order that they thought I would like to review them in, I am impressed by their algorithm as I find it incredibly useful. Statistics were provided on each one, a link to their site, their twitter page, followers, those they follow and more.
Usefulness of Mr. Tweet
I found this tool to be well worth the wait, and it was free. Definitely follow @mrtweet and here are the creators if you with to follow them as well: @mingyeow and @ambivalence.