PodcastAlley.com — the place to find podcasts. A good set of reviews on podcasting software.
The main ones seem to be “iPodder”:http://ipodder.sourceforge.net and “Doppler Radio”:http://dopplerradio.net.
It also looks like there are literally hundreds of Podcasts. Most are nerdy topics like Slashdot. Perhaps the most interesting for those of us who care about music is “DownloadRadio.org”:http://downloadradio.org. It uses the three magic technologies to bring you store-and-forward radio. That is RSS feeds to notify you of content, BitTorrent to bring you the bits over broadband and iPod/iTunes as a standard way to listen to it. Pretty cool.