While trying to track down a picture of "cesium atoms arranged to spell IBM" that
fenwickrysen mentioned here, I came across this site. Under the picture of the people is a link to "Nanoworld Image Gallery". I'm amused at the way so many of these look like surface plots of mathematical expressions. I'm not surprised by that at all, and I know it sounds kind of "well, duh, what were you expecting", but it's still interesting to notice.