What can you do with rooftops?
Some people are taking a stab at putting gardens on city rooftops (awesome idea!)
But what about suburbia?
My first thought is, create a business that acquires the license to use a rooftop, acquire as many as possible.
Then use this real estate you have effectively leased for many things, maybe solar generation? (then in effect you have your own power generation company). Advertising?!? Water collection (which you then sell on). The list goes on.
What would you do?