Walter Kauffman was a great historian of philosophy. More than any other single person, he was responsible for making Nietzsche a philosopher worth studying in the post-WWII era (as well as Kierkegaard and a range of existentialist thinkers). Open Culture has made available recordings of three lectures he gave in 1960 about Kierkegaard, Nietzsche, and Sartre, and the nature of philosophy. They are wonderfully erudite, graceful, and funny.
USUPhilosophy 