(I am not sure if I could make a sustainable business out of it, or even a fundable business, but a chaumian blinded digital token system (software and then multiple hosting options) where people got to then run their own arbitrary currencies, with a lot of them choosing to do commodity or equity/debt currencies, would be a pretty awesome thing. It would probably cost $2-5mm to do, though, and while I think you could avoid most legal challenges by separating out the software dev vs. hosting mints vs. hosting exchange vs. currency underwriting vs. marketing vs. wallets vs. merchant services vs. end users, I'm not sure how you could realistically make money doing it.)