My next project is to take these really cool Nixie Tubes and make a clock with an Arduino.
The guy from Scott Bot (http://scott-bot.com/nixie-bot/) is helping me out a lot by providing me with his board design and permissions to redistribute on my github with creative commons license. I'm going to make a few modifications to his board, a 5v, 12v, and ground pin out, as I want to add bluetooth and possibly other things to this board.
Some of the things I thought of were having a system on my Ubuntu Machine which allows sending messages (numeric only) via Bluetooth (http interface) to the clock. I'm going to write a weather perl script to grab the current weather information (change rain and temperature) for my area.
One other thing the Bluetooth will come in handy for is NTP (Network Time Protocol). I will do a few pings to find out a delay to talk with the clock, then I will send the time with the offset to set the clock to be as accurate as possible. This will make it so I don't have to implement buttons to set the time.
I also thought of adding an LED strip for accents, but that would cost quite a bit extra so I threw that out the door with having the the 12V pin out for possible future addition.