If you've got some spare time and plenty of LEDs, then a great project to build is this "Mega Clock" as described by Instructables member Michaelsky. The clock uses lines of LEDs to match every possible position used by hands of an analogue clock, and a digital display in the centre.
This design allows for many effects using the individual LEDs, all of which are driven by shift registers from an Arduino Mega or compatible board. An acrylic photo frame is used for a neat enclosure, which can be obtained from any discount store. Watch the following video for a demonstration of the clock in action:
This is a great example of what's possible with an Arduino - and all the details can be found in the project page. And for more, we're on facebook, twitter and Google+, so follow us for news and product updates as well.
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.