In my Careers class in high school, we learned that it is proper interview etiquette to send a thank you note to your interviewers. As long as the note itself is not too cheesy or brown nosing, I do not see how anyone would look down on a note of thanks. Most people I know enjoy being thanked, and I, in my honest opinion, find it unorthodox that people are rejecting the idea of sending a post-thank you note, whether by email or snail mail.
I sent thank you cards to everyone I met at my interview, and I guess it definitely did not hurt me, because I got accepted.