So you are looking for the perfect gift for the math geek in your life? The Fibonacci Clock fits the bill. This geeky clock has 10 color palettes and 2 lamp modes. It tells the time using Fibonacci squares. When there are more than one way to display a certain time, the light sequences are randomized.
Hackers can change the code using the Arduino IDE. This is an open source product. You can order one of these on ThinkGeek.