Congrats, Mr.A. I would definitely second Meth's suggestion of interviewfeedback.com. It was the most useful aid that I had. I would also recommend (and I know it sounds a bit odd) to stage a mock interview or two. You will never know how you will come across until you are in front of someone else. Have someone ask (and think hard about the answers) the typical questions, "Why do you want to be a doctor? What's the hardest thing you have had to do? What do you think of the health care situation today? What would you do to change it? Why do you want to come to our school? And my personal favorite: "I will be representing you to the admissions committee. What should I tell them about you?" HAVE AN ANSWER!
Investigate the school and ask questions. My stock question for my interviewers was, "What is in your opinion the strongest part of the curriculum at this school?". Know about the school, what the preferred teaching method is (problem-based, didactic, etc). Be current on issues of health care. Have some idea about how HMOs work, how much money the US spends on health care, etc.
Pretty much all this information is available online. It just takes time to find it all.
Geo