Zipf's Law says that frequency is inversely proportional to rank, i.e., the second most common word in a large body of text will occur half as many times as the most common. I have observed an even steeper curve for Software Carpentry feedback: of the 336 corrections I've received, 212 are from one person (Adam Goucher), 21 from Matthew Moelter, 12 from the next two people, and then we're down into the curve's long tail. Has anyone ever done similar stats on the volume or frequency of contributions to software projects?