I've been a fan of Arduino for years now, and have used it for building everything from MIDI controllers to simple LED flashers. One thing that has always intrigued me has been visualizing some of the data that I read off of the Arduino Pins.
Plot.ly makes this simple. Really simple.
The purpose of this instructable is to demonstrate how to hook up an Arduino + Ethernet Shield and send data to Plot.ly's Servers and create beautiful graphs. We will be using a dual temperature+humidity sensor (DHT22), and sending the results directly to Plotly.