Its basically a suped up version of KOS, which keeps a database of every opposite faction person you had seen and when you last saw them, as well as kill/death/times-seen information. It let you assign people to be on friendly or at war. As well as letting you sort the database view to descending/assesending on any of the information it contains, IE person who killed me most/ you killed most, guild that killed you most etc etc. It also showed on the map where you killed people and got killed by people.
If anyone has a mod that does this for TBC I would be greatly appreciated, or if someone wants to start one ^_^;