Organic light-emitting diode (OLED) displays are the coolest displays ever made. Check out this instructable on building an Arduino controlled OLED clock that uses a DS3231 RTC module for precise time-keeping. The DS3231 is a low-cost, extremely accurate I2C realtime clock (RTC) with an integrated temperature compensated crystal oscillator (TCXO) and crystal. The project incorporates a rechargeable battery to maintain accurate timekeeping during power failure. The implementation of an interactive menu system, which is navigated through two tact switches, the time setting becomes handy. The DS3231 module uses the built-in temperature sensor to compensate for clock drift due to temperature variation, which helps to keep the accuracy to 1 or 2 minutes/year. By default, the temperature is sensed and updated by the DS3231 once every 64 seconds. However, it is possible through software to update temperature reading and oscillator adjustment done as fast as 5 times/second. The temperature measurements are also displayed on the OLED clock screen. The author uses Adafruits Graphics library to drive the OLED display, which has the SSD1306 controller.
Arduino OLED clock