I stayed at a town in Turkey, Trabzon I think, where the whole town seemed to run on a related concept - the "taxibus". It was very low tech, based purely on flagging down a taxibus that looked like it was going the right way, but it worked extremely well. Price was reasonable, the town was full of them so it was easy to get a ride, and you got exactly where you were going unlike with a bus. I've been wanting to see a higher tech version for larger towns / cities ever since.