The Arduino project makes low-cost, open source microcontrollers that are easy to program using the free Arduino IDE, which runs on OS X, Windows, or Linux. The control language syntax is based on a simplified C/C++ language library. Extensible hardware daughter boards called shields allow for Ethernet, Wi-Fi, color displays, motion sensors, GPS, Zigbee, Bluetooth, or even robot motors with wheels. Arduinos can be controlled through sensors or Ethernet/Wi-Fi connections to activate lights, motors -- virtually anything the designer chooses. Complete kits with sensors and actuators are available directly from Arduino or numerous resellers. As little as $100 buys you a front-row seat in the Internet of things.
-- Joseph Roth