Identica, Twitter, and similar services tell you how many people are “following” you. Of course, it just means “are subscribed to you” — it’s not like they’ll follow your orders or something. Though I haven’t tested that hypothesis.
Anyway, let’s call that number F.
Now, I wonder if any services present an interesting (and in some situations perhaps more useful) variation on that number:
R == the sum of X over all of one's followers, where for each follower, X == 1 / the total number of people that follower is following
Then, for any given person on the service, I want to see R and F together, and I wonder if the ratio R/F would vary wildly. I think it might :-).