SpokenWord.org aggregates podcasts, almost all of which are free, and makes it easy for users to export them to, say, iTunes. It's a non-profit site and is all about the openness. (Disclosure: I'm on its board.)
The site is, let's say, very busy graphically, with a bunch of different ways to find what you want or browse to discover something good to listen to. But, now SpokenWord is looking for volunteers to curate podcast feeds and episodes in topics that interest them. These curated collections will be the main feature at the SpokenWord site, because nothing knows what's interesting to humans better than other humans do. Details here.