Are there any good podcast directories out there?

I have been primarily using my Fuze to listen to podcasts lately.  Where does everyone find their podcasts?  Are there any “libraries” or “directories” of podcasts by subject out there?  The ability to synch or update automatically is not that important to me.  I just want to know the best place to search for them.  I have a handful of websites bookmarked that provide free podcasts on subjects of interest to me, but I am interested in finding more out there and don’t know where to start.

Google is your friend.

Yes, certainly I have used Google.  I am interested in what others have used and like, and why.  Many that I have tried were not user-friendly, did not have a good search interface, or were plagued with annoying pop-ups.  Perhaps there are some good ones out there that I have missed that others would recommend.