If possible, I would suggest that you write a letter to the interviewer thanking him/her for his time and to reinforce your suitability for the position. Also, offer a means for them to contact you if they need more information..

I make this a normal practice (unless one of them is your close friend, then exclude him). If possible, get their business cards after the interview to facilitate this. In the world of competitive interviews, every thing that can set you up front among the other candidates go a long way.

hehe I did that.. Wrote to the interviewer, CEO and President..