The ESP8266 is a great cost effective module to add to any Arduino project for communication.
It is a $3 wifi-to-serial module with minimal parts and a simple command set.
Want to make a remote temperature sensor ? What about remotely controlling a light bulb ?
Possibly checking the status of your train while away ?
I ordered a few of these a while ago and finally got around to setting up a test circuit. Read more to see the circuit and details.