Regarding f.lux: I've been using it for years. It's good. But it doesn't help here. (It does make the white color a bit more bearable, but I need more.)
Regarding Windows themes: I already use an awesome dark theme for Windows 7 that I made. It's great. But the theme has little to do with this case. The theme has no effect on the page color in Chrome.
JoTo: I'm happy to find another fanatic of dark backgrounds
If you use Chrome, I recommend the Hacker Vision extension.
I still hope that someone could come up with a solution for me...