Twitterfriends is another of those interesting tools to see who you converse with most on twitter. You can see who replies to you most, who you reply to most, the sphere of influence and more. As a result it’s a good tool with which to establish who are the interesting people to continue following as well as those that may be worth dropping.
In particular the second to last tab deals with inactive account. It’s a quick and easy way to see which accounts are no longer worth following. The network tab is also interesting. It’s a quick way of seeing who is in your networki graphicaly. Click the FOAF (friend of a friend) tab and you can see how your network and that of others interact.
As more people use the website so the value of those figures go up. You’ll notice that according to this I have received no replies. If that was a reality I would have given up on twitter a few months ago.