If you're interested in competitive gaming and skill rankings such as the ELO system (used by chess players and also by Yahoo! Games) and Microsoft's TrueSkill, this article is well worth a read. It delves into the intricacies of ELO and looks at other ranking systems designed to combat its flaws, such as the eGenesis Ranking System developed for A Tale in the Desert.

It also covers tournament ranking systems, such as the well-known double elimination system used in many professional gaming tournaments. As the prize funds and public awareness of these tournaments increase, it's essential to ensure a fair competition for everyone, so don't be too surprised to see mathematicians with clipboards observing the next gaming tourney you go to.