This is basically a lazy web entry. I'm hoping that someone can come up with some javascript that would allow the user to see what the shadow of a stick would look like anywhere in the world at any time.
Basically the thing would work like a sundial at various times of the day in various locations, that is, if the sun was always out. Through javascript you could alter the locaction and the stick's shadow would reflect the change. Maybe you could adjust the time, but that would be a bonus. The key thing would be to know what the shadows would be like in any place in the world. At twilight, things would get hazy and after that the screen would grow dark.
The Virtual Sundial folks have created something very interesting, but it seems much more complicated than what I'm thinking of.
The New Yorker has an interesting article on "tangle diseases" -- Alzheimer's, Parkinson's, and A.L.S. Paul Cox, an ethnobotanist, and not a professional neurologists, hypothesizes that those who suffer from tangle diseases -- classified because of the similar ways that neurofibrillary matter is tangled -- is the result of absorbing neurotoxins in our diet. Mainstream scientists have significant problems with Cox's research, written up with Oliver Sacks. But it makes for a good story, and I'm always a sucker for a good unified theory.