With the Arduino platform it's easy to make a clock that's accurate and also interesting with regards to the style of output. Apart from the obvious choices like LCD modules, 7-segment LEDs and binary clocks, you can also interface with devices from the past such as Nixie tubes and vacuum-fluorescent displays. One interesting example of a VFD clock has been constructed by Kerry Wong, who based his clock around an Arduino-compatible circuit with an accurate DS3232 real-time clock and a VFD from old test equipment.
However instead of using specific VFD driver ICs, Kerry has created the required filament driver himself using a 555 timer IC, and the segment control is via TTL ICs and then darlington driver ICs that can handle the higher voltages. Finally, the entire project is mounted in a nice enclosure and demonstrated in the following video:
It's an interesting combination of contemporary and past technology, so visit Kerry's interesting website for more details. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
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.