Yep! GiantBomb is a video game website with some interesting personality. Something like 80% of their content is freely available with banner ads on the site and typical interstitials on their podcasts. For $50 a year, all ads disappear, the extra 20% content is available, and you get authenticated RSS feeds for the same podcasts minus ads that go into Overcast nicely. I love subscribing.

While that's an extremely niche website, I would happily subscribe to NPR, for example, in return for ad-free podcast feeds.

I mourn the death of the RSS reader and really really want RSS to continue to be an open model for distributing podcasts. But that being said, a business that handled premium subscription sales and also ad-sales for a publisher could do the unenviable work of inserting ads and distributing multiple feeds for free or premium users.