"Ok - I know this might seem backwards, but here me out. You can use *coughs* iTunes *coughs* to get more FREE podcast content on your Zune... Let's face it. Zune doesn't have a ton of choices (yet) while iTunes, which has been at this for quite some time now, has a huge selection ready for download! They're in the same format (mp4) and once you get them to the Zune Software, you can manage them from there - all you need is the initial download from iTunes! So If you can bear using that 'other' media software, click to find out how...."
I can't bring myself to say more about this. Those needing a larger podcast database should by all means find themselves satisfied with iTunes' more mature collection. Just don't come back wondering what that funky odor coming from your keyboard is.
Check ZuneBoards for an excellent and picture-filled step-by-step. Just keep in mind that only the new Zune models (the 4/8 and 80) can natively read mp4 files. If you have a 30, the software'll automatically transcode to a lower-quality file.