I like to play tennis, especially on the Wii where I don't have to leave the couch to score an ace. But while Wii Sports tennis is a very fun game--and it uses the Wii's accelerometers well--it's not the real thing. Some people want to play real tennis in the real world. And some people like to win.
Because of this, Mans Shapshak, an avid tennis player as well as a gear hacker, has come up with a novel way to combine fake tennis with real tennis to improve his real-world game using a hacked Wiimote.
The Wiimote uses Bluetooth as its wireless connection; thus with a little work it can communicate with other Bluetooth devices, like laptops. Then, combining the wireless aspect with some open-source Wiimote libraries, some basic coding, and a bit of simple math, Shapshak was able to start tracking his toss and serve. Then he started graphing his results.
By using the data as performance feedback he can practice more efficiently and, hopefully, get a more consistent serve. The same idea could be used for bowling, golf, or any other sport. I'd like to use it for kickball (my sport of choice) but can't fathom running around with a Wiimote taped to my leg.
Actually, yes I can. I am that guy.