Speaking of great coffee mugs, I have the all time winner but I'll have to dig through some stuff that's packed safely away to find it and photograph it because I'm finding no images on the web. Some years ago the NYC medical examiner's office had a limited quantity of mugs made up just for fun, for in-house employees, and a friend who was working there gave me one. I forget what it said or what the image was, but it had a thermal design that, when heated by the coffee, a "window" into the cup turned blood red.
Okay, okay, I'll go down to the basement and find which box it's in. Sometime this weekend.