CUNY Lecture Series- Lotsa interestic speeches here.
WPRB Princeton's (and the man behind MY Pal God Records, Tom knows who he is and he has called into TBS before) Jon Solomon used to have a great podcast called Local Support, but I don't think it's being updated anymore.
I tried following Planet Money, but couldn't stand the people behind it.
And sometimes I like to use the iTunes univesrity, you can get some intersting lectures from Stanford, Berkeley, etc.
Just now I was also been listening to the "White House Tapes" series from American Public Media, covering JFK, LBJ and Nixon.