Discarded and unused electrical devices can be harvested for all sorts of useful parts - and when it's hard rubbish collection week all those inkject printers are great for stepper motors. Another great find are VFD (vacuum fluorescent displays) used in appliances for time displays, and a neat example of reusing such a VFD has been demonstrated by Jimdo from the CPU Museum.
As you can see from the image below, a four-digit VFD has been used as the display for a neat clock, controlled by an Arduino-compatible. One point of difference with working with VFDs against LEDs and other displays is the method of driving the display, and some great notes on determining pinouts and control methods are given so you can work on random units yourself.
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.