http://www.lostateminor.com/2010/11/10/useful-iphone-apps-that-someone-should-build/
While I realize these are meant to be a joke, the ultimate frisbee one would be kind of interesting… Not for the frisbee part, but a similar interests kind of thing. Maybe just to see who is in the area that, lets say, makes games with Unity. Not necessarily contact them, because I’m sure there would be spamming of some sort, but just a similar interest kind of thing.
I could actually write/develop Ex girlfriend radar for Android. But her device had to be rooted and boyfriend would need to install apk on her phone (5 minutes, plug phone to puter and mount internal SD as disc drive, copy apk, unplug phone, install apk and delete it from SD).
It would also be good for spying over spouses and quietly/stealthy keeping eye on kids. But problem would be the size of the market and effective marketing strategy. Too much work for very uncertain results. Simply because rooting phone is not very end user friendly process and not many ppl out there are going through the process.
O-o Being that I rooted my phone, it’s not that hard of a process if you understand anything in the command prompt, and can read simple tutorials.