Check out this post on lifehacker. You can see what the screen looks like and you can maybe replicate it on Linux. Someone in comments has a suggestion for Linux too:

http://lifehacker.com/software/featured-mac-download/enable-...

You can get the same thing in Linux installing Compiz/Beryl and it's "Negative" plugin. Once active just press Super+m (Super is the "Windows" key) to "negate" the screen.

Alt+Shift+Print Screen for those on Windows.

http://www.wikihow.com/Invert-Colors-on-Your-Windows-XP

Tried it. It works, but it looks sooo shitty.

That's true. I've been using it all day though, and my eyes definitely feel better. It's kinda growing on me.