Nice. I've got a minor obsession with alternative ways of displaying the time of day. I've made a canvas clock or two of my own, and I used
http://www.let.rug.nl/kleiweg/abclock/ glued to my root window for the longest time.
I like that your clock simply displays the time of day as a visual ratio of time elapsed to time remaining. Of course, at the one-second-per-pixel scale, getting the precise time of day at a glance is a little tough.
Have you considered using color to earmark blocks of time? If it's 300 pixels wide, then a row is 5 minutes. Have you tried maybe some pinstriping on each sixth row to show hour marks? Maybe wider, like 2-hour blocks? I think it would give a lot more information in a single glance.
Do you think turning it 90 degrees and having it progress left to right would be easier or more intuitive?
And what about the size? 300x288 has its advantages, but have you played with other aspect ratios?
I'm not trying to pick apart your work, I'm trying to suggest different ways to take it because I like what you've done.
If you want to return fire, I made http://slumberheart.com/things/clock.html earlier this year and would love to hear some suggestions.