Richard Burton has a new-ish blog with some interesting, clock related stuff. Half of the blog is devoted to his restoration of an actual, mechanical turret clock and the other half is a very nice collection of his C code for the ESP8266, mainly related to the DS3231 RTC. As well as the driver for the DS3231 (and the EEPROM usually found on the same PCB with these devices), he also has a simple NTP client (for setting the time) and timezone support.
Definitely worth a visit!
esp8266hints 