You know how a jar of natural peanut butter separates into two layers: a rock hard layer of solid peanut particles on the bottom, and a liquid layer of oil that splashes onto the kitchen counter and your clothes when you try to stir the two layers together?
John Falk Kelly didn't like it when that happened, so he came up with a way to mix peanut butter easily. From Wired's How-To Wiki:
When you buy a jar of all-natural peanut butter, don't stick it in the pantry. Park it on top of the refrigerator, upside down. Once a day, when you walk by it, say "hello peanut butter", and flip it over.
When you're ready to open it and stir it up, it will be half mixed for you (and not hardened into a frustrating marble block).
He says he was so pleased with the results, that filed a patent on it: U.S. Patent # 6,325,533.
I'm thinking someone could make a version of this that used some of the same circuitry and components in the hourglass random number generator project I posted earlier today. The jar of peanut butter would go where the hourglass is. The gadget could either sense the opacity of the oil and flip it when it was no longer translucent, or it could just flip it once or twice a day.