First, I love the book review podcasts. I generally listen to the NYTimes Book Review, Nancy Pearl's BookLust and the Horn Book podcasts while I walk in the neighborhood. Most are pretty good, although I found it ironic that the only book review podcast with advertising is the one from NPR! I particularly like the ones that offer something more than what's in the print offerings, otherwise what's the point? I often skip through parts I'm not interested in, but I also find myself listening to things I wouldn't have heard before.
I just discovered Nancy Keane's Booktalks--Quick and Simple podcast, visible here but I can't seem to find a way to get it other than on iTunes, which works for me, but not everyone. Most of these are just a couple of minutes long, but when I subscribed and asked to "get all" I ended up downloading 732! Good thing they're all so short!
I also occasionally listen to other stuff like Jane Brody's health tidbits and my kids love Crazy Dave's Kid Show, a call-in show for kids based in central Iowa. Go figure.