CensusPlus

CensusPlus is a mod which records details about the characters online on your faction's side at the time of the polling. This is done with the liberal use of the in-game /who command. The information is then stored in the CensusPlus.lua in your account's SavedVariables folder which you can then upload to websites like WarcraftRealms.com. Sites like these sort the information and then display it on their site in chart and graph form.

URL
URL : http://www.warcraftrealms.com/censusplus.php

Current version
The most recent version is v4.2.2, released on January 30th, 2009. The first Wrath of the Lich King-compatible version, v4.1.9, was released on October 17, 2008.

Current version highlights

 * Wrath of the Lich King compatible
 * Tracks Death Knights as well as base classes
 * Tracks from levels 10 to 80
 * Fixes the infamous "/who frame pops up at random" bug of past versions.