A lot of hardware builds have been submitted to the list Clocks for Social Good, this is a little different, this is a software clock that can be shared over twitter, the original tweet can be found here:
The KIM Uno replica was used as a host for a program to display time. It has a RAM and an EEPROM area. The RAM area was used to store the time variables. The program resides in EEPROM, thus it only has to be entered once. On future power ups, all that needs to be done is to set the time and start the clock.
To set the time, memory location 0x0024 needs to be set with the seconds, 0x0025 with the minutes and 0x0026 with the hours. To keep the program size to a minimum, no validation for a valid time is made, if the values exceed 59 for the minutes and seconds and 23 for the hours, the clock will simply increment them until they rollover back to 0 after reaching 99. Eventually they will rollover to valid values, but it may take a few days for that to happen.
This project made it to the hackaday.com front-page, [Al Wiliams] wrote this great analysis: http://hackaday.com/2015/09/29/kim-1-clock/
thanks for this, I have included the code and the clock works accurate with settings 30 and 9C. A higher second value is better for fine adjusting.