Build a small wearable instrument to check UV index, air temperature, humidity and air pressure. Using this data you can avoid sunburn, and possibly predict weather changes or storms. Also handy to monitor Indoor humidity.

humidity monitor

Components required:

1× Sharp Memory LCD
128px * 128px - monochrome
1× ATMEL ATtiny861A
picopower risc cpu
1× si1132
UV sensor
1× si7020
humidity sensor
1× lps25hb
pressure & temp sensor
1× CR2016
coin cell
1× some resistors & cap's

See the full build at; https://hackaday.io/project/4706-uv-badge