I enjoy these fine fellows:

Adam Carolla
Marc Maron
Greg Fitzsimmons
Smodcast (Kevin Smith)

I like Adam C, and I've heard so many good things about his podcast. It's something I ought to like a lot. But... I can't stand to sit through it a bit. Marc Maron is OK. Smodcast is sometimes entertaining.

I personally like these dudes a whole lot: Comedy Death Ray

I also enjoy the Hardcore History podcast by Dan Carlin.

ooh, I see the hardcore history one -- that looks interesting!