I interview quite a bit of people. I always do it in a laid back, conversational style. When I ask technical questions, somewhere towards the middle or end of the session, I do it because I just want to know that the person I talked with understands some fundamentals (it's never a tricky question; just something basic like creating some threads, etc).

I talk with them about their previous work, stuff they're proud of, their hobbies and other things. I've recruited teams that excelled compared to their peers, and were certainly more fun than others.