I am a fan of logic puzzles; problems that, once you know the answer, are sooooooo simple, yet at times very difficult to solve. I don't mean " if two trains.." or "if my aunt is my mother's brother's barber...", but something like the following:
(This is one I used to hear when applying for programming jobs)
There is a cake, with one piece already cut from it. How would you cut the remaining cake in half ?
Everything you need to know is in those two sentences. There is no 'trick', just a simple answer. If you like, I can post more later. Oh, if after a week or so, no one gets the answer, for a small fee I will post it!
Enjoy, and please post your favs.