Alltop is a new (2008) endeavor by Will Mayall, Kathryn Henkens, and the famous Guy Kawasaki, the same crew that built the Trumours site.

Alltop is an organized "top sites" feed-reader, categorized and hand-picked. They have a category just for podcasts here:

http://podcasts.alltop.com/

You can't add your own feeds, but it seems they have a plan for keeping the most relevant and high-quality feeds on the page. Give it a look and see what you think.