If I had access to a time machine, what would I do?
First I'd go back in time and stop Hitler, obviously.
But high on the list would be going back to 2007.
I'd storm the stage when Steve Jobs was introducing the iPhone.
"I'm from the future and this device will become the single most important computing device in the world. For the love of god do not allow Apple to only run apps they sign, that's insane!"