by ohneschuh @ instructables.com:
I read about the ESP8266 first in March this year and I didn’t know what to do with. And now I’m really fascinated how easy the connection of an Arduino to the Internet can be. Like others I set up a weather station on a breadboard first and sent data to thingspeak.com. This ends up in a highly condensed stripboard layout and the needed software package.
What are the functionalities?
measure temperature, humidity, pressure and illuminance (brightness)!
send all data to thingspeak
ESP8266 can be turned on and off by Arduino for energy saving
additional digital IOs
Runs on 5 to 12 V
and a lot more
ESP8266 Weather Station with Arduino – [Link]