If you don't know about Michael Ramirez's cartoons, I suggest you buy his book , Ramirez, a winner of Pulitzer Prize, is among the foremost artists and most astute political commentators of our time.
UPDATE: Here is an excerpts from Ramirez's book that would like to share with you:
Albert Einstein once said, "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe." Einstein was right. It is this axiom that makes political cartooning important. They people who ultimately govern will make mistakes. They are human, after all. But history has demonstrated that power can turn leaders into monsters. Editorial cartoonists will gladly point out that shortcomings of the powerful in an effort to keep them human.