This brought a chuckle. I’ve always enjoyed posing questions that no one else would think of asking…

http://www.kottke.org/08/04/helicopter-on-a-turntable

As to the airplane-on-a-conveyer-belt question, the answer seems to be resolved:

http://www.kottke.org/08/01/mythbusters-airplane-on-a-conveyor-belt

What I love about it is not just that someone thought it’d be cute to present their answer in the BIGGEST POSSIBLE TYPE, but that the next person took it and put it on a T-shirt for purchase. The world is certainly shrinking.