I have been enjoying a "radio theater" podcast produced in Canada by a group called Decoder Ring Theater. I'm specifically indulging in their "Red Panda" super-hero comics-on-the-radio. If you've got elementary-age or older kids, they'll probably dig these. If you yourself are a kid at heart, you'll enjoy them, too.
I find that podcasts like this are a nice treat on long car trips. I hook up my iPod through the radio and the kids can listen to it that way.