MakeTime is a clock that uses a ring of 24 RGB LEDs to display time. Hours and minutes are displayed using different colors. As it uses just 24 LEDs, its granularity is 2.5 minutes. The time can be set using its single button, located in the center of the clock face.
MakeTime is also an Arduino-compatible development platform, and is designed with hacking in mind. In addition to the addressable LEDs, the button and the DS3231 RTC, you can access many of the Arduino pins on an optional expansion header.