The primary hardware you need in addition to the EAUduino itself is a special cable that translates USB into TTL serial. This cable is called "FTDI TTL-232R USB-to-TTL serial cable" and can be purchased from a variety of sources.

It can be purchased from Modern Devices here. (Scroll down)

Or, you can buy it from Wulfden here. (Again, scroll down.) 

 (Various members of our project team report good quality and service from both companies.)

You can also buy it directly from the manufacturer here.

The cable costs around $20 plus shipping; and using the cable instead of incorporating that functionality into the board makes the EAUduino less expensive to build.

Moreover, the cable won't go to waste! It is completely compatible with the Sanguino, the Barebones Board and numerous other Freeduino platforms. 

The Eauduino is a Freeduino variant of the popular Arduino physical computing platform that includes commonly-required support circuits not present in official Arduinos, including a Real-time Clock, a driver for driving up to four relays and an inverting Schmitt trigger for push-button and other inputs. It is programmable from the standard Arduino IDE using a USB to TTL serial cable.

The goal of the Eauduino design is to create a deployable/embeddable platform. In other words, you develop the software on it for your application, and then deploy that same board. The Eauduino is optimized for what could be described as "external control applications" because that's where the idea came from.

One member of the Eauduino team is a farmer who keeps a few (10-12) chickens in the frigid northern plains. He needed a device that would control a heating element to keep their water from freezing without overheating it, and he also wanted to turn on one space heater if the temperature is under 10F, and a second if the temperature was under 0F. Along with this, he wanted to make sure the chickens got 8 hours of light a day, so he wanted a light turned on from 8am-4pm -- but only if the ambient light level was below a certain threshold.

Obviously, this is all doable using various industrial controls connected together with bailing wire; but the result turned out to be fairly expensive -- about $350 for just the controls. For that price he'd be better off just eating the chickens and buying his own eggs, so a more cost-effective solution was needed.

It just so happens that the farmer is also an electrical engineer, so the precursor to the Eauduino was born. After several improvements and iterations, the Eauduino as it exists today is now available to all under the Creative Commons Attribution Share-Alike License.