Why Do You Stay Up So Late? (interactive Flash @ Born Magazine)
Or, if you prefer, read the unenhanced poem by Marvin Bell.
Thanks to Metafilter for reminding me about this piece.
(Please note that my screenshot is greenish because when I work late into the night, I tend to use Tint Screen, a cross-platform widget.)
If you’re ever looking for a more system-level/integrated solution than Tint Screen, you might try creating a custom ColorSync profile that you can just switch to in System Preferences/Displays/Color. I have one called Green Tint that’s easier on the eyes when I’m just staring at text.