a basketball, equipped with accelerometer, gyroscope, bluetooth! Get states on your shot, the arch, the spin, dribble patterns, the strength of your pass.
see trends in your improvement over time, compete against friends in the quantified baller app (trololol...) etc etc!
I had an old nexus, made a small android app which sends the accelerometer and gyroscope readings to a restful api hooked up to meteor. meteor doesn't support rest just yet, so I used the meteor router library, and embedded the sensor data into the url of a GET request. the server then extracted the data from the URL, and sent a Meteor Alert to all clients listening. The client was basically a webapp using Chart.js to plot the sensor readings in real-time.
I never really used js or meteor before, which is why this is so janky. the code is just.....beautifully messy. I think only 30% of it is being used, Im probably making over 3k requests per second to the server, I cope pasted the chart rendering code like...6 times............ ya.
We can take this idea, and apply it to all sporting goods! Yay! Now I can sleep!