Medium of Exchange... this here is a big one, that cryptos may solve, but we have to reinvent the wheel.

Basically, when i create a widget, i should also create the money to purchase the widget. The money and the widget should cancel themselves out when all the trades are done. The money should not continue on buying things, it should be used up. The money should equal the goods that are to be sold.

But, this requires weird transaction into the future...

There have been several people working on this problem.

However, the best solution will be something like computer-aided barter.