We never tire of interesting clock projects, and the following example published on the x2jiggy website will appeal to the IT or mathematically-included enthusiast. They've taken the typical binary clock project to the next level by fitting it inside an old hard drive enclosure. With some effort the facing surface has been polished for a great effect.
Furthermore with the use of an external real-time clock IC the time will stay accurate and offers other options such as dates, alarms and more. To save space and funds a whole board wasn't used - instead a bare Arduino-compatible circuit based around an ATmega328P with Arduino bootloader. Overall it's a great clock that would look good on any desk or make a nice gift, for example:
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.