I love John Stewart. He takes the easy route, admittedly, in that he tears down more arguments than he offers of his own (I say 'easy', because it's incredible how much hypocrisy can be documented from politicians/newsfolk/commentators from their own broadcasts).
It's sad that his formula works so well: 1) Show what X person is saying on TV now. 2) Show what X person said just a few weeks/months ago. 3) Point out the obvious discrepancy. It's especially easy to do with the right, though I've seen a few good ones from Stewart concerning the left.