GPS location and movement data is what gives Google maps its near-real-time view of traffic on all roads, and busy-ness of all shops.

I think they collect location data from people riding public transport so they can tell you how long people wait on average at bus stops before getting on a bus.

Does Google collect atmospheric pressure readings from phone altimeters and use it for weather models? Could they?

Kindle collects details on books people read, how far they read, where they stop, which sections they highlight and quote, which words they look up in dictionaries.

I wonder if anyone’s curated a list of things like this which do happen or have been tried, excluding the “gathers user data for advertising” category which would become the biggest one, drowning out everything else.

I think current phones use accelerometer data to detect possible car crashes and call emergency services. Google could use that in aggregate to identify accident blackspots but I don’t know if they do. But that would be less useful because the police already know everywhere a big accident happens because people call the police. So that’s data easily found a different way.