Time is a precious gift too
After a job interview, a thank-you note is strongly suggested. Not only could this be your last chance to express what you didn't express properly during the interview, but it also shows that you are polite, responsible, appreciative of the interviewer's time, and still thinking about the job when you leave.

The interview thank-you is a different sort of note from the others, however. They should be short and to the point, and they should not be very personal… but they should still be detailed and give examples. Definitely thank the interviewer for taking the time to meet with you. Refer to something you spoke about during the meeting, or introduce a new idea relating to something you spoke about. Be brief in saying goodbye. Example:

Dear (name of interviewer)(double-check spelling of name),

Thanks for meeting with me on (day of week). I was thinking about what you said about (subject). I would be a good person for this position because I (your experience related to subject). Again, I appreciate your time. If I can give you any more information, feel free to (preferred method of communication) me at (number or address of contact).

Sincerely,
(Your name)

Does that help? You're welcome.