Services that happen during a ride. People will no longer have to drive during their commute. This will drive longer commutes.
What will people do with all that time? Basically the same things they do now with down time - surf Facebook, watch movies, watch porn, watch online classes. I think it will drive an increase in passive entertainment. Games that go well with riding in a car might be more attractive.
Similarly, people will be trying to work more while in the car to make use of the time they're no longer at the wheel. So any services now pitched at executives who have personal drivers could be pitched to anyone. Any product that makes it easier to work in the car - in-car office setups - will sell big.
More generally, now that you don't have to drive, there is a lot of room for car customizations. As long as you can meet safety requirements, you can personalize your much more. No need for the classic arrangement. This will be even more true for electric cars as the drive train has far fewer form factor requirements. So I suspect there will be a lot of crazy customizations out there.