I never realised so many adults watched cartoons.
Aqua Teens is certainly no "Simpsons," but I enjoy the twelve minutes of humor they provide per episode.
Adult Swim, which is non-kid-friendly cartoons on late at night on Cartoon Network, is pretty popular. They've got a show on now called "Metalocalypse" that's I find pretty funny. It's a send up on metal bands. Also, South Park is very political, and often friendly to conservatives (very friendly to libertarians). And the Simpsons is enormously popular/successful.