I am using the barometers in the galaxy nexus and the other phones. We have a couple thousand users submitting to pressureNET (free on the Android market) so far. Expanding as fast as we can!

did you think that you can measure such weather params as air humidity or rainfalls/snowfalls by how they affect signal strength between fixed transmitters/receivers (e.g. cell signal strength to handset when it is stationary at home at night? :) just my 5 cents