How to list this accomplishment on my vita? I just saw that one of my research articles was the most-read paper in one of the top journals in my field in February of this year.  What is the appropriate way, if any, to list this on a vita?  It's not an "Award", strictly speaking, so would it be best to just list it as a comment next to the paper?
Great work ! The way I do it is under the Publications section of my CV. The following citation is formatted in the ACM style. You can modify it for your own citation styles.

J1. Smith, J. 2013. "The best paper ever". ACM Transactions of Awesomeness, 1 (4). ACM Press, NY, USA. (most read article in March 2013)