Someone should write a website or app for crowdsourced, distributed carpooling. It would probably have to include some kind of reputation system for drivers and passengers, because it would mean a lot of strangers driving around other strangers, and there might be a conflict with the taxi drivers union or whatever they have. Still, there are a lot of cars on the roads these days, and most of them have room for more than the people they carry. Besides that, sharing driving between two or more people is more economical than public transport, with added flexibility to go right to your door if needed. All that's really missing is a way to hook up willing drivers with regular paying passengers, and that's just a technology problem, which the world is great at solving.
Mokalus of Borg
PS - Apparently this has been at least one person's thesis topic.
PPS - I'm not sure whether it involved any practical coding or demonstration.