We never tire of Nixie tube clock projects, and another example by Ian Sparks uses a single digit tube mounted in an unorthodox fashion. Instead of building a clock that keeps the tube and high-voltage driver circuitry hidden from the end user, this clock is quite the opposite to the point where a PCB is not used.
The circuit is constructed using exposed copper wire which looks great but is also quite damngerous - thus the term "Deadly Nixie Tube Clock". Based arourd a bare Arduino-compatible circuit the clock is easy to modify and interfaces neatly with an accurate real-time clock IC. Furthermore, the result is quite a work of art, as shown below:
The most important part of any clock project is the inclusion of an accurate real-time clock IC. Here at Freetronics we have the Maxim DS3232 real-time clock IC module:
Apart from keeping accurate time for years due to the temperature-controlled oscillator and having a tiny coin-cell for backup, it is very simple to connect to your Arduino project. A driver library allows your program to easily set or read the time and date. Perfect for clock projects, dataloggers or anything that needs to know the date and time. Furthermore it contains a digital thermometer and 236 bytes of non-volatile memory to store user settings and other data. For more information, check out the module page here.