As a huge fan of the television series 24, I have often debated this concept with myself, since torture for the greater good is a central role in the show. The main character often tortures people to serve the greater good. He is persecuted for his actions, which he feels is unjust since harming one "criminal" saves thousands of innocent lives. If you are interested in the subject of torture, I would highly recommend this series.
Personally, the only way I could see torture being justified is if the person in question is a PROVEN criminal, and the information could stop a catastrophe. Even then, it feels wrong to me though... but I understand that a greater good is sometimes beyond a necessary evil. I wouldn't feel bad about the torture if the information saved the lives of my children.