as a counselor and now a program director, I really like open-ended questions that allow the potential staff member to tell me about themselves. These are also the questions that I feel are most effective for me to communicate some of the opportunities that I've had. My favorites are similar to:

How would your friends describe you?

What is a difficult situation that you dealt with, how did it turn out, and how did you feel about it?

What is the hardest type of person for you to work with?

and my personal favorite, for creativity sake, is :

Tell me about the letter J, its characteristics, and its placement in the alphabet. (see their creativity, and get them to say that it is the 10th letter of the alphabet. will they tell you how they figured that out?) This one works better for in-person interviews and could be valuable for quick interviews such as those at summer job fairs.