Well... I think that if I could have a superpower just for 24 hours I'd like to be able to do something in those 24hrs that could last really long in time, so I would feel satisfied.Something that Nobody can change after months or years. I'd think about being able to change a lot of crappy laws that exist in the world, but lets face it, governments do whatever they want with the law anytime they want, and it would take me more than 24 hrs.
Maybe I'd like to be able to identify terrible ideas or intentions of people and take them out of their heads, and it will take some time for them to incubate them again...
I'd have to somehow connect to everyone in the world, Charles Xavier-like, and do this.
I am very sure that we'd benefit a lot in the following months.