Maintained by North Dakota State University, this web site charts "family" trees for mathematicians, based on their supervisors and their students.  If anyone sets one up for philosophy, let me know, and I’ll publicize it.  It might be interesting (or at least amusing). 

For example, my supervisor was Peter Railton, whose supervisor was David Lewis, whose supervisor was W.V.O. Quine, whose supervisor was…I forget now (C.I. Lewis?  Whitehead?).  (I’ve since "produced" one PhD student, with others in the pipeline!)  John Rawls had many "offspring":  Elizabeth Anderson, Samuel Freeman, Allan Gibbard, Jean Hampton, Barbara Herman, and Christine Korsgaard, among many others.  Each of them, in turn, trained many students.  Among Quine’s many offspring were Gilbert Harman, who, in turn, "produced" Stephen Stich (among many others), who, in turn, "produced" Robert Cummins, Thomas Ricketts, William Ramsey, Shaun Nichols, Ted Warfield, and many others.  My colleague A.P.D. Mourelatos was supervised by Wilfrid Sellars; Mourelatos, in turn, trained Herbert Granger, Steven Strange, Daniel Graham, and Victor Caston, among many others.

UPDATE:  Brian Weatherson (Philosophy, Cornell) writes:  "The mathematical geneology project already encompasses part of the philosophy family tree. For
instance, Quine is there, with 19 students (including Harman, Lewis,
Charles Parsons and others) and 104 descendants. It’s obviously biased at this stage towards students in mathematics – Lewis for instance is only listed as having one descendant, but there is already something of a start."  And my philosophical colleague Josh Dever tells me he has compiled some genealogical material like this on philosophers, which he may be able to put into a form that can be circulated.

ANOTHER UPDATE:  Reader Patrick O’Donnell usefully suggests that I mention "Randall Collins’ The Sociology of Philosophies: A Global Theory of Intellectual Change (1998) as exemplifying the importance of something like ‘family trees’ for philosophy, or at least providing some of the theoretical vocabulary and variables useful for assessing the significance of such phenomena."