Couple of books I found useful :-
A more beautiful question - Warren Berger Power Questions - Andrew Sobel Secrets of Question Based Selling - Thomas Freese.
I like to probe for curiosity.
Q: You've read the position summary, company profile, and met with other members of the team. What questions do you have now? What more would you like to know about us?
On this subject of questions, Andrew Sobel has a good read> http://www.goodreads.com/book/show/13510967-power-questions-...
