I didn't know i could crave a cube hardboiled egg... until now. Andrew Huff has a nice flickr set of the egg cuber in action - apparenly this is some retro device that i've missed out on?
You take your hardboiled egg while warm, stick it in here, screw the cap down, and *poof* square egg? Lots of various pictures and video below...







The Egg-citing Egg Cuber and an Egg, Squared.