The Mathematics Genealogy project is a huge database of mathematicians, where and when they got their degrees, and who their advisors were.  (There’s also a wiki-based Philosophy Genealogy.)  Nice pastime when the polar vortex keeps you from leaving the house: find famous people in your academic family tree.

If you’re in the Mathematics Genealogy, you can use Geneagrapher by David Alber to produce a graphical genealogy.  It’s pretty amazing. Here is mine (click for full size):

TIL: Mersenne and Copernicus are in that tree.