People have used 8x8 LED modules as graphical clock displays, forming digits, but I wanted something more obscure.
This clock counts off seconds on the rightmost display. The catch is that the dots appear haphazardly, controlled by a random-number generator. If the next randomly-generated dot has already been lighted, the program generates another until it finds an unused spot.
The left and middle displays are hours and minutes, and this is the exasperating part because to tell time you have to count the dots. This is easy at 3 in the morning, but of course this is set up as a 24-hour clock, and counting all those dots isn't easy. And to make this worse, the clock generates a new random pattern on the hours and minutes display every time a minute turns over.
This was mostly an exercise in linking modules and in array programming, but I learned a lot from it. Except what time it is.