One of the things I found interesting about the old Motorola Xoom (one of the first Android tablets) was that it had a barometer sensor. It seemed like a great feature to enable crowdsourcing weather information. As the Xoom faded from my memory so did the notion of having a barometer on me all the time.
Listening to a discussion of all the sensors in the new Nexus 5, I wondered what sensors my previous generation Nexus 4 has. So, I installed CPU-Z and learned the 4 does indeed have a barometer. I haven’t found any app/service that crowdsources barometer sensor data. However, there are a few free Android apps that work with the sensor. I’m trying Barometer Monitor right now.