After coming across a commercial flip-dot display (as used in destination indicators and other displays that require excellent visibility in direct sunlight) David Henshaw spent considerable time and effort by adding Arduino-powered circuitry to convert the display into a neat clock.
The results are fantastic, and with enough circuitry (including a lot of H-bridge ICs to handle the change of polarity requried for each dot) the Arduino can individually control each dot in the display. This gives the user a great amount of freedom to create visual effects and display more than simple numbers. However as a clock the display is a success, a demonstration of which is shown in the following video:
The most important part of any clock or timer-based 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.