Okay, I have a power, it is not a glamourous power by any strech of the imagination but it is the most powerful one I can think off.
The power to control poo.
I know it sounds junvenille but think about it. Firstly, I could use this power to clean the earths water supply and treat sewage. I could keep everyone`s system regular improving everyone`s health. Lastly, I could have ultimate political control by threatening the digestive system of politicians and world leaders. Imagine how quickly some foreign policy would change if a political leader was stuck with constipation or diarrhoea for days or even weeks. This power could disable whole armies with a sudden attack of violent diarrhoea and bring an end to warfare. Finally, noone would want to kill me because I am helping the enviroment. I would become a great hero, but no-one would want to talk or sit next to me much.