The Parallax Digital I/O Board Kit enables your microcontroller to interface to high voltage circuits allowing you to read up to eight optically isolated inputs and control up to eight isolated outputs. Inputs can be a voltage from 5-30VDC (AC compatible) and outputs can be either mechanical or solid state relays that can switch up to 8A loads, such as cooling fans, solenoids, heating elements, and more.
Get it here:
http://www.ic0nstrux.com/products/development-kits/Digital-IO-Board-Kit
Digital I/O Board Kit
What if you could control the lights of your house with your microcontroller?
