I listen to a whole lot of podcasts to unwind. In no particular order I would suggest:
This American Life (NPR)
Wait Wait...Don't Tell Me (NPR)
Risk! (Stand up Comedy)
Basically any podcast produced by Howstuffworks.com is fantastic.
If you're a sports fan I also listen to Around the Horn, and PTI. The B.S. Report covers a wide variety of topics, mostly centered around sports, but they have lots of other things that gets covered.
I also listen to a whole lot more (more political things) but these are my favorite unwinding podcasts. Political podcasts just end up making me cranky
Glad you're liking the zombie podcast!