RadioLab (variety of topics in the hard and social sciences)
Invisibilia (focuses more on behavioral sciences -- "the invisible forces that shape our lives")
The Moth (real people telling real stories)
Selected Shorts (actors reading excellent short stories)
99% invisible (can't describe this quickly, but generally fascinating cultural analysis)
Stuff You Missed in History Class
Wait Wait Don't Tell Me (NPR news quiz show that has been *savage* the past 2 years)

Also slowing working my way through the Doctor Who: Verity! backlog