Danny Baker discovered the hard way that you can't make money out of podcasts. His "All Day Breakfast Show" started off free but closed down only a few months after they started charging a fee. As far as I know, no-one else has tried to do the same thing since then.
Of course, most podcasts are either radio shows re-packaged, or are run by newspapers or magazines to promote their website. However, there are a few notable exceptions:
Herrin and Collings is a very amateur production (it's recorded on an Apple Mac in Richard Herring's attic). Journalist and broadcaster Andrew Collins is the straight man to comedian Herring, and they fill an hour or so talking about stories from the day's newspapers. Apparently Herring used to be a regular guest on Collins's Sunday show on (BBC Radio) 6 Music, and they seem to have quite a good rapport.
Phill and Phil's Perfect Ten is rather more professional (it's recorded in a studio, and they have announcements read out by Stephen Fry), and ostensibly it's more structured (in that they supposedly answer 10 questions from listeners). However, basically it's the same concept - two blokes talking away about whatever they want.
Here the two blokes are Phill Jupitus (comedian, longtime team captain on "Never Mind the Buzzcocks", former presenter of the breakfast show on 6 Music), and Phil Wilding (who was the producer of his radio shows, and previously worked at GLR with Danny Baker). And, yes, they have a website
The theory is that they have exactly 30 minutes to answer 10 randomly selected questions, but they often start with something like "why did you go to Wembley Stadium this weekend?", which clearly didn't come from a listener and simply gives them the excuse to talk about anything at all. Entertaining enough if slightly self-indulgent.
Phill Jupitus can also be heard on The Game podcast (from The Times), and Andrew Collins sometimes fills in for Mark Kermode on the Friday film podcast, but I guess they get paid for those gigs.
So why do a podcast for no money?
Herring and Collins did a talk to the Radio Academy about their podcasts, and they said that it does give them each a higher profile for the work they do (probably more for Herring's stand-up comedy) as well as advertising their availability for a radio show - though it might be hard to accept the constraints of a show on the BBC after the freedom of being able to say whatever you like on a podcast. Maybe it has even worked for Danny Baker, because he now presents 606 once a week (also available as a podcast) and is the temporar.y replacement for Jonathan Ross on Radio 2.
One standalone podcast that isn't presented by a has-been DJ is Stephen Fry's Podgram. Far less frequent, shorter, not so funny, and clearly more of a vanity project than anything else - I doubt he is looking for any more work. Of course he has a website