As a massive consumer of Podcasts I check out many depending on my frame of mood:

The Dollop - American (and occasionally world) history that explores the truly absurb and lunatic parts of the timeline in an incredibly hilarious way. Their live shows with special guests take the comedy to an entirely different level.
The 1908 New York to Paris car race is spectacular.

Tim Ferris - the guests Tim manages to get are nothing short of amazing and there are episodes that are absolutely essential listening. You walk away with a far deeper appreciation of the guest and their incredible journey in their respective fields.
Highly recommended the Jamie Foxx, Arnold Swartzenager, Richard Betts, Charles Poloquin

For wrestling chat Killing the Town is a bit of fun but I find the Chris Jericho, Steve Austin chats a bit more polished especially if they get a naturally chatty guest like Paul Heyman or Daniel Bryan.

Finally there's Dad's life through iTunes and for one of the most awkward yet thoroughly entertaining listens of all time you must try My Dad Wrote A Porno - these guys have been a massive tour after the podcast took off and it's definately one to check out.