It's safe to say that how you end a note says a lot about who you are and your intentions toward the recipient. The same applies for American corporate etiquette and the way in which we conclude our thoughts in an email. It's important to be friendly but not too familiar. I think the absence of a written conclusion also says something about your expectations for the receiver.
Some people even brand themselves with how they end an email. My friend Rob, for instance, is a motivational speaker and always ends his emails with "keep on smiling." Not only is it a throwback to his favorite quote, but a life dedicated to helping others feel their finest.
Three years ago I picked up the habit of ending my emails with "Best." It was the perfect pronunciation of how I wanted others to feel at the close of my communication with them. I'm fairly certain that I lent it from my college buddy Lance Hagaman. Perhaps, then, the way in which we conclude our correspondences is a direct reflection of not only our intentions toward the recipient, but also our homage to an individual who at one point inspired us.