There are the watches, the LED clocks, the LCD clocks, the flip clocks, the nixie clocks, and the scope clock.

The Scope Clock is a clock that uses an oscilloscope tube to display the time, giving it a very original look.

Check it out here !

Note: OZ2CPU, who made a cool home made watercooling system, also made his scope clock:

The photo in this post is from OZ2CPU's scope clock page and is published here with his kind permission.