There's no limit to the amount or type of clocks that have been developed around the Arduino platform, using all sorts of imaginative and normal items to display the time. However the "PlotClock" by Johannes takes this to a new level by drawing the time using a whiteboard marker, and erasing it before drawing the next time update.
The clock is driven by an Arduino board controlling three servos - one to lift the marker up and down, and another two to control the X- and Y-axis position of the marker - and thus control the writing. Consider the demonstration in the following video:
This has to be one of the best executions of a clock device we've seen in a long time. For more information you can download the Arduino sketch, and the files to 3D-print the required parts. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're interested in experimenting with Arduino for your own inventions - but not sure how to learn - order one of our Experimenter's Kit for Arduino:
The package includes a wide variety of parts, sensors and modules including: a servo motor, lights, buttons, switches, sound, sensors, breadboard, wires and more. Furthermore a Freetronics Eleven Arduino-compatible board is included to make this an extensive hobby experimenter, inventor and starter kit.