I've always wanted to know the MAX speed of my serve. Too bad I'm not in the US to have that tech.
But I was figuring if I could get sb else to start a counter, maybe with my cell phones chronometer which also registers 100's of a second, and then stop it when it reaches the end of the court.
Of course you would have to carry a meter around to measure the lenght of the court to get the speed . First I would count the speed in meters by secound and after that convert it to Km/h.
Of course maybe for you guys would be mi/h but you might get the idea.