This app will tell you your kill/death ratio in the Call of Duty games. More importantly, it tells you how many kills you need to "boost" your kill death ratio up by 0.01 via the Kill Death Calculator tab. It can also tell you how many deaths will lower your ratio, if you click on the Death Kill Calculator tab.
A calculator that estimates the chances of getting a killstreak in the various Call of Duty games based on a highly tested and credible algorithm I developed.
Modern Warfare 3 (when released)
Modern Warfare 2
World at War
Modern Warfare 1