What questions should I ask at the end of an interview?

What are some good questions one should ask Facebook interviewers after the end of an interview?

• At the end of your interview Facebook, Google employees ask you if you have any questions for them. I have a heard that they consider the quality of question asked by you as a measure of your knowledge about the company. What type of questions one should ask at such a time to make a good impression, few examples would be great.

• Answer:

  What's the answer to the ultimate question of life, the universe and everything? I would open with that. Seriously now, I'm not a programmer but my common sense says that you should ask what you genuinely want to know. Ask about aspects or specific projects you'd be interested in working in, ask about specific flaws or imperfections of their service/site/API (especially if you think you have a solution), show your curiosity as it not only reflects true interest in what they do, but also an inquisitive nature (in the good sense). If they are offering you a chance to ask them questions, seize it (yet don't go overboard either, remember, common sense). If you don't have questions, or are struggling to find them, then you simply might not be what they are looking for, and that might probably go for you too.