To expand on the bus route thing: City of Houston just completed a complete revamp of their routes. It would be interesting to see how much, if any, that impacted uber's use in areas that should in fact have better (more direct) service.
Second item is DUI rates before and after Uber comes to town. For that matter how much surge pricing happens during major events such as concerts, football games, etc where people may perceive they must drive. Combine that with congestion data and perhaps uber can propose a partnership with the local metro to pick people up outside of the deepest traffic area by doing a bus/rail hop first.
For instance Houston has light rail from our sporting venues to park and ride lots. If you can group people going to the same neighborhood it's possible to shift congestion and make the last mile cheaper for riders and more environmentally friendly to boot.
You also have major events where really no one should be driving but they are so data is gathered: hurricanes, ice storms, blizzards and so on. In Houston we have regular flooding and it would be interesting to see where reroutes happen due to deep water and it would be very useful to have drivers marking flooded spots so it can be shared back to other drivers via Waze/Google Maps and maybe even CoH fire and police.
I could easily see an autonomous car on the side of the road with an led bar in its back window or on its roof warning that water is 12" past this point. Many of the worst spots have machine vision readable flood gauges but even for those that don't it may be possible to gather surface elevation from the Google maps car since they have such accurate GPS, and that data doesn't change often.
In fact one could see Uber / Google subleasing a few of those cars to HPD just for the purpose of sending them out to gather data (including video) on flooded intersections so police could spend their attention elsewhere. And of course so they'll know if someone does flood themselves out anyway by driving past the car and then stalling. Autonomous cars already track object distance and speed of vehicles in their view.