To make up for using a FizzBuzz-like question in the last entry (Hey, the title does stress "quick" doesn't it?), I will follow up with a thoughtful and practical question. This one is somewhat technology dependent but could be potentially reworded to be more agnostic.
NOTE: As an interview question, I wouldn't recommend asking this unless the candidate claims to have .NET knowledge. This usually comes in conjunction with a pure coding whiteboarding problem.
QUESTION:
Describe a couple different approaches to managing ASP.NET Session State in a distributed fashion. (You get extra points if you've never had to deal with this problem and had to come up with something on the spot. Usually, people that fall into this group are more likely to come up with unique approaches.)