Legion of Skanks comedy podcast -
http://legionofskanks.libsyn.com/ .
Joe Rogan is good depending on the guest.
NPR has good stuff in the form of All Things Considered, This American Life, Wait, Wait Don't Tell me, Radio Lab, Fresh Air, Leonard Lopate, Studio 360, and Selected Shorts.
Brilliant Idiots -
http://soundcloud.com/thebrilliantidiots .
Combat Jack and Juan Epstein, if you're into rap.
I'm pretty sure all of these are on Itunes, Stitcher, or Libsyn .
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Also Opie and Anthony, Classic Stern, and Ron and Fez all have classic shows usually on Youtube.
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Darkness Radio is pretty good, if you like paranormal stuff. It's on Itunes, etc....
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Not a huge audiobook guy, if I can lay my hands on a ebook or paper copy, but James Ellroy, Robert Crais, Lawrence Block, and Michael Connelly all have nice easy listening versions of their books.
You can find many by youtubeing the author's name + audiobook, then setting the time parameters for 20 minutes + , if you want to preview them. For instance, here's a copy of Colin Quinn's fun read, "The Coloring Book" that someone snuck up -
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Also you can find many full length comedy specials on Youtube that are worth a listen.