1. Try to find the owner of the iPhone and return it to him.
2. Report at the police station.
3. Tweak the settings, copy all interesting data to your phone/drive and throw it away.
4. Unscrew it and exploit it's internal components.
5. Sell it.
6. Keep it.
7. Gift it to your friend.
8. Other (Please mention)
См. статью: If you found a new iPhone 5 in the washroom, what will you do with it?