Check out the 12 entries to the UCS editorial cartoon contest (2011 edition) AND VOTE. I'll add my favorites later, but they are all winners.
2011 Cartoon Contest Contestants | Union of Concerned Scientists
Here are three of my favorites, although it was tough to pick just three.
I'll update this later with my thoughts on these and the other entrants and add my rationale behind choosing these three. Can you guess which I voted for?
Spot the human artifact - on Mars!
4 hours ago in The Phytophactor