I finally have artnet working with the Teensy 3 micro controller / development board. The result is a simple and cost effective way to control led lighting from your computer via the ethernet cable output. Using this set up you can control hundreds of leds, output video to leds, or whatever.
You will need to use some software on your computer as an artnet output, I use pixelcontroller. This is free and robust, and fast at processing data, so frame rate is good. You can also use something like Max.
here is a video of simple output:
The description and code are in two parts: