Dougs official website: http://www.dougswordclock.com/. Instructable for the Arduino version: http://www.instructables.com/id/The-Word-Clock-Arduino-Version/.
For source code of this clock: see http://git.luon.net/?p=users/paul/wordclock.git.
Some ideas to do with this clock (in no particular order):
add wifi module
synchronize time with pc / ntp
flash lights when you have an appointment in your Google agenda
adjust brightness based on calculated sunrise/sunset times http://www.codeproject.com/KB/cs/suntimes.aspx.
fade words in/out
blink leds (blink first led slow when it is 2:00:01, blink fast when it is 2:00:59; if it is 2:01:01: first led is solid, second led blinks slow)