In conjunction with the new site design Jin has proposed, we may get to choose images to put on the 404 error and captcha pages. (I'm not sure if there are any other pages there are that we can customize, but if so, I hope someone else will edit them in.) The main theme is pretty clean and not very physics-specific, but these error pages are a good chance to work some inside jokes and physics references into the site design.
A few possibilities for the 404 page were proposed on the original design thread (though one of them may not be 404 material much longer :-P). We can reconsider those, and also collect new ones if anyone has them. So, what ideas do we have?