If you've ever dabbled in HTML, you'd know about hexadecimal color codes—those base-16 numbers that mix red, green and blue to create a precise hue. This mesmerizing Colour Clock takes the current time, converts it into a hexadecimal value, and uses the ever-changing shade as its background color. A screensaver for Macs can be downloaded too. [The Colour Clock via Geekosystem]