I've been using
Juice to download and manage podcasts on my Mac for quite some time now. When Apple added podcast support to iTunes, I though about just using that, but there are a few things I don't like about the way iTunes does stuff. Also, iTunes doesn't have BitTorrent support, and a couple of the podcasts I subscribe to use BT. Juice is pretty good, but it's a bit slow on my machine, and there are a few quirks. I'd like to try out
Transistr, but it's been in "coming soon" mode since January, I think.
This recent blog post indicates that they're making progress on it, though. I don't know if there are any other good podcatchers for the Mac.