Smile!

When you greet them, shake their hands and smile. It puts you at ease and makes them like you better. Most people act terrified during an interview. If you can pull off an air of being at ease with the situation, they will respect you a lot more.

If you are especially witty and bold, try to pull of a joke. Don't make it too canned or corny, and nothing even remotely offensive. I've gotten people to laugh in an interview and it nearly always scores major points. If you can make people laugh, not only will they like you more, they will admire your ability to handle a pressure situation with humor. If you can somehow work humor into your answer, you will really stand out.