Gamification is the only area where you really can't run out of ideas. Find ways to pull some of this sensor data, whether from the smartphone, the Nike+, the fitbit, etc, and create games out of it. That would also seem to be a good easy way for a young developer to get something simple but finished (rather than complex but unfinished).
It could be just a basic competition among friends -- whoever walks the most steps in a day gets a badge. Or you could do something crazy like Pokemon Go except where the Pokemons run away from you at a 10 minute mile pace (6 mph) when you spot them, and you have to chase them down. Or do an internet-of-things project where you change your TV channel by doing the corresponding number of push-ups. These ideas are free of charge, you're welcome.