I love Penn & Teller. I've seen their show in Vegas twice and seriously hurt myself laughing at their stuff. Their best stuff though, in my opinion, is their show on Showtime, Bullshit. Not sure if this video appeared on the Bullshit show, but it's a pretty good slap at the idiots who still think that 9/11 was planned and executed by George W. Bush.
I don't agree with everything they cover, but for the most part, it's pretty interesting. But probably not safe for work, unless you have headphones. Also, another video here that's pretty slick.