I'm a lousy interviewer. That's why I hate having to do them.
I don't care about how the candidate feels, what he had for lunch, etc. etc. I just want to know how technically capable the person is since I'm deciding wheter or not to hire said person to assist me in developement.
The way I interview people is simple, first I ask them what kind of projects they might have done. Then from there I process to poke and prod them to see how much they understand what they've done, I usually start from the simple and mundane like What is a dataset? Then I'd proceed to something that requires a bit more understanding of how stuff works like Could you explain how the ASP.Net runtime knows which button you clicked? And then from there I'd move to the tougher questions like What is an IHTTPHandler and why would you use it?
To some people it seems like I'm picking on some mundane question like What is a dataset? or How does a form post back to the server? The reason I ask these questions is that while undoubtedly the person is able to code I need to know if he understands WHY things are working. ASP.Net has a lot of plumbing involved and while you don't need to know exactly how things work, it's best if you at least know how data passes from the browser to the server to the .Net runtime. Also I want to see if the person truly understands what they are doing, or just coding for the sake of it.
Through my questioning I also like to see how the person tackles questions when they don't know the answer, people who are straight and direct will immediately say that they don't no the answer after giving it some thought. People who try to potray themselves as a valuable hire when they aren't will fire off on all cylinders until they realised that I'm not impressed at all with the jargon they're spewing.