I think the coolest thing about self-driving cars is they can create a mesh network with one another. If I'm driving to work and a traffic accident occurs 2 miles ahead on my route, with multiple self-driving cars present at the accident, those cars can share traffic information with all self-driving cars in the area. My car will then plan an alternative route around the accident before I've even seen it.

Communication would be encrypted of course to prevent tampering.