There is a ton of good stuff in the Brew Strong and Jamil Show archives from 2006-2008, although personally I don't listen to the current shows hardly at all anymore from about 2009 onwards because they're constantly off topic and it drives me nuts wading through 4 hours of garbage to get nearly zero nuggets of good information.
The most informative and creative podcasts I think are Basic Brewing Radio with James Spencer (Arkansas), and the now defunct Craft Brewer Radio with Graham Sanders (Queensland, Australia). Craft Brewer podcasts are available only if you know the secret handshake. The website was torn down when he got himself into some legal issues back in 2009 or so. But Basic Brewing is going on all the time and they run a lot of cool experiments. James can be dry in his humor and presentation, but every episode is chock full of good lessons and information. As for Graham, he had a zany sense of humor and a big ego, but when it came down to it, he truly had the most kickbutt show, I think, with a lot of good ideas that were largely outside the box / non-conventional. If you can seek and find those podcasts, it's well worth a taste. I really wish he'd start up another show. But I believe he said he's retired for good, and he'll just laugh at you if you ask him where to find the old episodes and tell you to find them yourself if you really care. What a guy, eh?!
I also enjoy Brew Bubbas with Craig Belanger, Jerry Jackson, and very often Todd Parker (Detroit). They aren't quite so deeply technical as other shows (though they do try). They also tend to talk more about the sheer enjoyment of beer and homebrewing and what's going on in their lives at the time as it relates to their love for beer. Kind of cool. Right now they are in the process of learning to become recognized BJCP judges, so that really is cool.
And now I just have started listening to Brad Smith's BeerSmith podcasts (or I guess I don't know exactly what he calls it). It seems he's been able to gather full panels of very well reknowned guests and they share their knowledge on specific topics in a very professional, straight-forward, no-nonsensical manner, which seems like it will work if you can do entirely without the occasional stupid joke from any of the other podcasts. Personally, I like a little humor so I don't know if I'm going to come to love this podcast or not, but it is certainly very informative and doesn't contain any fluff. No advertisements or promotional stuff or any of that jazz... nice.
In the end, try them all and see what works for you. If you are a complete nerd (like so many of us), then you'll listen to and enjoy all of them eventually.