What to write in a thank you email or letter

What should you write in a Thank You email or letter? How about starting it off with a "Thank you for the opportunity to interview at Medical School X"?  The following are some ideas on what else to add in your note.

1. Memorable conversations: If you and your interviewer talked a lot about a passion for the violin or triathalons, you should add that into the note to make it more personalized.  That extra special conversation will make you a memorable candidate.
2. Special things about the program: Add information on a special program the school offers that you would be interested in participating in and say why.
3. Plug in why you would be a special fit for the program: Remind the interviewer of why you want to go to that school and why the school should accept you.  The last push to get an acceptance!
4. People: Comment about how the medical students and faculty were approachable.

Close off the email by telling them that if they had any further questions to feel free to contact you by email or phone.