I had mentioned a wide background in security on my resume. Someone I came to respect a great deal was interviewing me. It was pretty obvious he was dealing with a problem in real time (like maybe right before the interview) with SSL. We had a conversation about how SSL works and why he was seeing the problem (a basic MitM issue). It was technical but conversational and dealt with a real, actual problem. I have a lot of experience explaining security related technical issues to people with no background in security so it went really well.

That, in contrast to the ridiculous questions interviewers ask about non-problems, was very refreshing and sticks in my mind.