Meet the Weather Point 2.0: a tiny gadget that measures temperature, humidity, UV, and atmospheric pressure and sends the data to your mobile device. The device is small enough to fit in the palm of your hand but has 4 sensors to get the job done. Thanks to these sensors, you can limit your exposure to UV rays or find out your current altitude more accurately.
Weather Point 2.0 does not require an internet connection to work. It attaches to your keychain and communicates with iOS/Android devices. The developers are planning to include a SDK for fetching sensor data. If you like this project, you can support it on Kickstarter.