As an update, I have redesigned the Arduino clock controller board - I decided that in reality all I needed was the ATMega Chip itself, and that placing an entire module was a waste of PCB space.
I have further updated it to version 3 - supporting a RTC chip, and reducing the size of the PCB.
Here is a photo of the v2 and v3 boards, and an assembly manual, (which I have been sending out with my kits) - That should make assembly easier for anybody who wants to make one themselves.
The new PCB
The new PCB that I designed has larger tracks, and larger pads, making assembly easier. When you look at the PDF, you will see that there are large copper masses 'directly over' existing tracks. Please don't worry - that is normal - it is a ground plane, and the track that it is over is the ground track. All of my boards try to use ground planes so that I have to etch less copper from the board.
Programming the new board:
One Idea I got from EvilMadScience.com, was to use one of their programming cables, instead of using an entire Duemilanove module. It is really cool - you pay $20, and you can use the cable for many many projects - all you have to do is include a trivial programming header on the PCB. The cable is available from: evilmadscience.com/partsmenu/130-usbttl
A New Display PCB
I have been designing a new display PCB - I can etch it on 2 6x6 inch pieces of single sided PCB stock - the neat thing about the new display, is that it gets cut into a set of "LED Strips", with each strip being used to illuminate a word. the spacing between LEDs is about 23mm, so I can use these strips to make BIG WORDS (Much larger than the 6 inch displays i have been making). The clock size that I am making currently will be about 240mm x 240mm for the word plane, set into a total display that is about 320x320, making a really nice wall clock - It will take a couple of weeks, but as soon as I have something more tangible to display, I will put it up here.
I etched the PCB over the Easter weekend, and am looking forward to making a bigger display.
Another side effect of the LED strips, is that you are not limited to English words - we can modify the software for any language, and you can use whatever size strips you need behind words to make the clock work!!!
Updated Software to allow the brightness to be reduced at night
I have modified the software to allow the brightness of the clock to be automatically adjusted based on the time - At 7pm, it will reduce the brightness, and at 7am, it will increase it again - This was to allow the clock to be less intrusive in my daughters bedroom.
Attached is the software that allows that to happen, and Matt Sparks DS1302 library. It is in the file Wordclock-reduced-brightness.zip attached to this step.