Reviewed in Best free apps without obstrusive ads
pressureNET is not beautiful or even directly useful (many other apps have much more functionality) but I am obliged to promote this app because it helps scientist to get atmospheric data from our devices. Do your part in helping advancing science!
Apposaurus: Developed by /u/cryptoz, this app crowd sources pressure information from barometers that are found in some smartphones. The information is anonymous, and is sent to researchers and forecasters to help with forecasting models, and to better understand atmospheric conditions on the ground. Negligible impact on battery.