Build a minimal ATmega328P circuit... so you don't need a full Arduino anymore. And learn something about logic gates along the way. This project aims at explaining how to build a minimal circuit ...

The ChronosMEGA watch took four months to build by Instructables member N.Fletch. It is powered by an Atmel ATmega328P QFP processor, which uses 10 Blue 1206 LEDs to indicate the time.