Although older Macs were built to last, sooner or later they will cash in their chips and join their now spiritual founder. However this shouldn't be a moment of sadness - especially for the Mac Mini. This was the situation facing Professor Shadoko, who turned this anto an opportunity... using some Arduino-based hardware and many LEDs turned his Mac Mini into a wonderful clock, for example:
You will see in the project that a MAX7219 LED driver IC is being used. To save money you can also use the AS1107 from Austria Microsystems which is often cheaper than the Maxim part in some markets.