Here are a few notes about interesting dev boards I have used for "Internet of Things (IoT)" projects.
The ESP8266 was developed as a wifi board, but its integrated micro controller makes it an interesting platform for lots of uses. By adding the Arduino Core you can program it using the Arduino environment. I have used ESP8266 on a number of projects successfully. It is a bit power hungry because of the wifi, but it has support for sleep mode between sensor readings and broadcasts that can prolong battery life. If the IoT device is connected to power then this is an easy choice, as it is so low cost, and wifi makes it easy to push data to a server.
- Sparkfun Thing - this hookup guide also describes using phant.io, SparkFun's free online data storage service.
- Adafruit Huzzah