Regarding job interviews, I usually sit on the other side of the table ;-)
I try candidates feel comfortable and calm, I guess it's the best way to know who is sitting in front of me and how well he or she fits into the vacancy.
However, everybody has heard about hard and unpleasant interviewers that try to bring to limit candidates to find out how they react in front of difficult situations, but I don't think this is the best way to manage an interview.