Post-Interview Thank You Notes
A guest post by Heather Johnson
It is now proper job-seeking etiquette to send your interviewer a thank you note when the first meeting is over. In fact, many hiring managers will take notice if you don't follow up with some sort of acknowledgment. Not only is a post-interview thank you note a great way to network, it can also help you clarify information that was discussed during (or omitted from) the meeting.
Handwritten Cards
The most common post-interview thank you notes are sent via snail mail. Any local greeting card store will sell a variety of thank you cards, but you don't need to be creative here. Avoid anything humorous or unprofessional. Ideally, you should choose a thank you card with a conservative cover and nothing written on the inside. You will handwrite this part.
If you have been corresponding with your would-be employer through email, it would not be deemed inappropriate to follow up in this fashion. Virtual correspondence is more commonplace in the business world than ever before. While you do not want to email a thank you "ecard," you can write a professional email to follow up and thank your interviewer for his or her time.
What to Say
Whether you are using snail mail or email, the sentiment will be the same. You will want to express how much you enjoyed meeting with your interviewer and thank him or her for the opportunity. You may wish to reiterate why you feel you are a good fit for the position. If you feel you left the interview without clarifying certain points, do so now.
Thank you notes can even give you a forum to do some damage control. If you were five minutes late to the interview due to traffic, for instance, you can express your regret again for the faux pas. Remember, this will be a hiring manager's last impression before he or she makes a decision. Use this medium wisely and you could increase your prospects of being short listed for the position.
Article courtesy of WorkBloom, an employment blog incorporating a comprehensive career resources section, including the largest database of professionally written resume and cover letter samples on the Web.

Good points. Additionally, I would recommend sending a thank you note even if you weren't chosen for the position.
Not only is this good professional etiquette, but if the chosen candidate doesn't work out for some reason, or a similar position opens up with the company, you could get another shot at interviewing or being hired outright.