I just read about this in the Kansas City Star, and found it interesting. It shows how many people might possibly keep track of you, based on who is on line right this instant that has you on their buddy lists.
To see how many people you are potentially connected with in Instant Messenger right now, go to aimfight.com, type in your screen name and a friend's (or an enemy's), and see who comes up with the higher score. The numbers do not reflect how many people actually have you on their buddy lists, as I understand: Click on "What is AIM Fight" and see if you understand how they come up with your score.
The number changes fast, depending on who is online. Very interesting.