First: 'Sorry about not touching this for four years. The nixies, ardunio, Arduinix™ and everything else have been waiting patiently while I went off and built some websites, consulted on some business startups, and began teaching at the college level.
Second: The software aspect of this project became more complicated quickly. I wrote code to do animations, transitions, etc., but the code got out of hand quickly. Early on I decided to just let the Arduino/Arduinix manage the nixies and not do anything more fancy on that side. I want to move all the other stuff to an object-oriented language on the host. I looked into extending the Firmata library and into writing my own communication protocol. I started learning how to talk to all the things Arduino from my MacBook Pro or Linux laptop.
That work was set aside when my consulting business heated up.
I got a Raspberry Pi for Christmas. What an exciting little machine! And what a wonderful community around the Raspberry Pi/Arduino interface and architecture. I decided to get back in the saddle and finish this project.
It won't be fast, but I'll publish my progress as I go. As I said, the next step is developing a simple but extensible communication protocol to tell the Arduino what to do with the Nixies from the Rapberry Pi. Then we'll go to town on the Pi side.
Thanks for your patience.