Still in Beta, NPR is building an index of Podcasts, which you can sort by topic, title or provider.
Of course, regular RSS feeds are available as well. (Please, just put the link for both media player formats on the page for each broadcast, do we really need to go to another page just to select which streaming format? Thanks NPR!)
For the record, I still think “podcast” is a bad name for this media distribution method. Media RSS seems to be more descriptive (because eventually people will also have to say “video podcast” or somesuch and so on…).