All the cooks out there know that there comes a time when recipes require you to separate the egg yolks from the whites. I remember when I was a little boy seeing people do that by breaking the shell roughly in two and pouring the egg into one of the halves. The yolk would get caught while the white would overflow the shell and pour into the bowl beneath. You would then pour the remainder into the now empty other half of the egg shell, with more white dripping down. By doing this several times, you get get a pretty good separation, though it required some skill to not shatter the shell while breaking it and not break the yolk on the jagged edges.
Now they have little plastic devices that consist of a small shallow cup with a collar around the lip separated by a gap. By pouring the egg into the shallow cup, only the yolk stays there while the white oozes through the gap into the bowl beneath.
That works pretty well and I had thought that that was the apex of egg-yolk separating technology, never to be improved for simplicity and effectiveness.
But I was wrong, as this video demonstrates, that uses simple physics principles.
(Via Cory Doctorow)