Double Bubble has a good little writeup on a pretty useful WoW-related iPhone application. But instead of the MMO, this app centers on another game in the WoW universe: the Trading Card Game. WoW Lifecounter (iTunes link) is a utility that will (you guessed it) count your life points as you play the TCG -- it tracks both sides' heroes, and you can take away or give life points with just the touch of a button. It's pretty simple -- all you do is punch in the starting health of each character, and then the app will even track wins for each side. Usually, you can just track the points with a pen and paper, but if you don't want to bother doing math in the heat of a battle, the app can be fun to use.
It's 99 cents, which might stop the cheap among you from picking it up -- we won't blame you if you'd just rather have a Junior Bacon Chee and write things down. But if you play the WoW TCG a lot and always have your iPhone with you, it's probably worth the investment.