This one was just too, too obvious once I got irinago's invite and realized that there's a group for this sort of thing.
I may have gotten the idea from a bit about how we see faces in everything from Scott McCloud's Understanding Comics, but I'm sure he's not the first person to point it out.
This was a terrible pain to take, because I just couldn't get low enough to frame and focus the shot without cranking my neck. Also, I usually frame macro shots by moving the subject, not the camera--the cheap ballhead I use has only two settings, "glued shut" and "floppy". It took me a whole lot of tries, but I'm finally happy with the shot.
Taken with a Nikon-mount Vivitar 80-200/4.5 macro, using a set of Nikon extension tubes.