Here is a template you can use to mail and / or email to the manager you interview with. I believe that if you are really interested in the position it is good to email this and snail mail a signed copy of this the same day you had the interview. I often recommend to candidates I have worked with to have this printed, in an envelope, and ready to mail. So when they leave the interview they can put a stamp on it and drop it in the nearest mail box. Often the larger office buildings have an out going mail drop near the elevators so just drop it in there so you know it will get to them the next day. Here is the general format:
Thank you for the time you shared with me Friday, as well as your candid disclosure of what you require in the candidate for ________________.
It was a pleasure learning more about your company and being able to see first hand your organization’s environment and to get a glimpse of how things operate. I believe my background, along with my enthusiasm towards being apart of your successful organization, makes me an excellent fit for this position.
I look forward to hearing about your decision soon.