way back when i was thinking about interviewing for microsoft (against my better judgement) i looked up some puzzles online. microsoft is famous (or infamous) for asking not only coding questions but also thinking questions (like "why are manhole covers round?") and puzzles. here's a site called www.techinterview.org that has some good ones if you're ever bored. a couple that i liked:

• a man has a gold chain with 7 links. he needs the service of a laborer for 7 days at a fee of one gold link per day. however, each day of work needs to be paid for separately. in other words, the worker must be paid each day after working and if the laborer is ever overpaid he will quit with the extra money. also he will never allow himself to be owed a link. what is the fewest # of cuts to the chain to facilitate this arrangement and how does that guarantee payment?
• you die and the devil says he'll let you go to heaven if you beat him in a game. the devil sits you down at a round table. he gives himself and you a huge pile of quarters. he says "ok, we'll take turns putting quarters down, no overlapping allowed, and the quarters must rest on the table surface. the first guy who can't put a quarter down loses." how do you make sure you win?