A Brief History of Mathematics is a BBC series of ten fifteen-minute podcasts by Professor Marcus du Sautoy about the history of mathematics from Newton and Leibniz to Nicolas Bourbaki, the pseudonym of a group of French 20th Century mathematicians. Among those covered by Professor du Sautoy are Euler, Fourier and Poincaré. The podcasts also include short interviews with people such as Brian Eno and Roger Penrose.
Mapping the Republic of Letters is a cartographic tool designed by students and professors at Stanford that seeks to represent the Enlightenment era Republic of Letters, the network of correspondence between the finest thinkers of the day, such as Voltaire, Leibniz, Rousseau, Newton, Diderot, Linnaeus, Franklin and countless others. Patricia Cohen wrote an article about Mapping the Republic of Letters as well as other datamining digital humanities projects in The New York Times. The mapping tool is fun to play with but I recommend you read the blogpost where Cohen explains how to use Mapping the Republic of Letters.