I looked most at Podcastalley.com (really like that name!) and explored some possibilities from areas of interest. Then, I branched out, going directly to some sites that I was fairly sure would also lead to podcasts of interest -- such as NPR and some related sites like Prairie Home Companion. Now I can listen to these favorites any time I want, even if I miss the regular broadcast. (I'm looking forward to listening to the podcast of Garrison Keillor's ALA speech soon, too.)
Yesterday on NPR, the on-air contestant on Weekend Edition's Sunday Puzzle program said she listens to a podcast of the puzzle because her local station doesn't broadcast it. This ironic sort of incident brought home to me what could be one of the most practical uses of podcasts!