Update ThingSpeak Channels and Twitter with Arduino Ethernet

This tutorial demonstrates how to use the Arduino to read in analog inputs and update a ThingSpeak Channel by sending an HTTP POST via the Arduino Ethernet Shield or the Arduino Ethernet (all-in-one). The analog input can be the output of a sensor, like a light sensor or temperature sensor. In addition to sensor data logging, this sketch updates a Twitter status every hour via ThingTweet.

Source : http://community.thingspeak.com/tutorials/arduino/update-thingspeak-channels-and-twitter-with-arduino-ethernet/