The Fibonacci Clock

Philippe Chrétien, a computer programmer and engineer, built this clock described on Instructables. The screen consists of five squares proportionate to the first five numbers in the Fibonnaci sequence. The hour is marked by the red square and the minutes with the green square. If the square is blue, that square illustrates both the hour and minute.

How do you tell the time? Chrétien explains the math:

To read the hour, simply add up the corresponding values of the red and blue squares. To read the minutes, do the same with the green and blue squares. The minutes are displayed in 5 minute increments (0 to 12) so you have to multiply your result by 5 to get the actual number.

-via Book of Joe