A couple days ago Michael Lugo at God Plays Dice shared a link to a mathematical relationships search. Enter the names of two people with PhDs in mathematics and it will spit out their academic relationship. For example, my advisor, John Franks, is my academic father and my good friend and collaborator Jim Wiseman is my academic brother. It draws the information from the Mathematics Genealogy Project.
It is fun to play with. For example, Euler is my great-great-great-great-great-great-great-great-great-great-grandfather and Erdős is my tenth cousin four times removed. By the way, I think I finally understand what it means to have nth cousin m times removed.
Interestingly when I look at my relationship to different mathematicians, it is often the case that our common ancestor is Simeon Poisson who had only three advisees: Chasles, Dirichlet, and Louiville.
There is another interesting website that performs a similar function. While the mathematical relationships search pulls information from the genealogical tree, the AMS runs a website that pulls information from the graph of collaborators (these data come from MathSciNet).
The collaboration distance generalizes the well known Erdős number. My Erdős number is 4; that means that I wrote a paper with someone who wrote a paper with someone who wrote a paper with someone who wrote a paper with Erdős. Similarly, my collaboration number with John Forbes Nash, Jr., Grisha Perelman, Steven Strogatz, and Terence Tao is 5 and my collaboration number with John H. Conway is 4.