This idea is so obvious it would not even be worth mentioning, were it not for the fact that I can’t find a discussion about it on the Internet. The only thing I can find is an article from 2002: http://www.nature.com/news/2002/021104/full/news021104-6.html
Why is the entire playing field for a sport, all of the players, and the ball somehow tracked electronically? Why in the world are football referees eyeballing whether or not a player crossed the goal-line for a touchdown or where to spot the ball after a player is tackled? Arbitrarily putting the ball down and then calling out the guys with the chains has got to be one of the dumbest rituals in all of sports.
RFID would seem to be a more reasonable easy way to make baseball, football, soccer, and even basketball (goal tending would be easy to track) would benefit from this.
I can’t even imagine the argument about slowing down the game would apply because you could built an interface to it that the refs can use immediately. If the ball in basketball is on the downturn when it’s tapped in the air, a little signal could vibrate in the ref’s pocket. If it doesn’t, then it doesn’t. When the ref wants to spot the ball to see if a team made a first down in football, a simple device could tell them approximately where to spot the ball and more importantly immediately tell the ref whether or not this was a first down.
Simple and no change to game play, and actually makes the game move faster in some cases.
Avichal Garg 
golf…golf…golf….when i first took my dad to walk with me for a round, he actually thought looking for the ball in the rough was part of the game! i know that the ball companies would rather that the ball be lost and a new one be bought more often, but i guess, with more expensive balls, they can make up for the loss in topline by having a healthier bottomline, what say?