I have to restrict it to just three questions, eh? This would depend on how many years of experience the person claims on their resume.
What is your strongest area of knowledge?
This is an easy one one to lure them in. Should tell you what they want to sell, too. Also, you can expand on this to see if you think they got all of those years of experience, or backdated a bit of their resume.
Why are you applying for this job?
Think about your own answer to this one. After all, it is better to be working with folks who share some goals (money, training, etc.)
What is your biggest screw-up, and what did you do about it?
If they say "I covered it up" tell them Enron is down the hall.
What is the level of dba ? In previous interviews, I gave them a quiz to test specifics before the interview. During the interview, I ask open-ended questions (Department Z needs a database installed - what questions do you need answered before starting) - similar to MCrowley. I like the screw-up question. Anyway, if you ask open-ended questions, after they have finished answering, I normally follow-up with give me an example ... Another useful question is - what have you learned about sql server that you could not find in a book - the nuances most of us have experienced.