Here are some of my favorites. I link to the website for each, but all are available via Itunes (except where noted).
The Slate Political Gabfest is a Friday AM ritual for me. Thirty minutes of political banter from a core group of Slate contributors.
My buddy Steve controls all media in Memphis and uses his excellent Book Talk podcast as the vehicle to reach his flock (download or RSS from website).
China Business Blog and Podcast is the best English language resource for information on business dealings in China. Front line insights and great guests and interviews.
Atlanta's own Valerie Jackson podcasts here Between the Lines radio show each week. Excellent interviews with fiction and non-fiction authors.
Q&A and After Words. Two C-SPAN staples. Usually post a few days after the Sunday broadcasts on TV.
History According to Bob is a daily 8-20 minute overview of some facet of history, from the Wild West to the 5th Italian War. This surely has a cult following.
Travels with Rick Steves. Rick's podcast covers world travel with the tone and humor of his European travel guides.
Special mention for the audio edition of the Economist. This is a word-for-word reading of the entire content of the magazine by professional voices.