I just went into OS X's keyboard shortcuts to disable the Alt-Esc Front Row combination (that I'm always hitting by mistake) and noticed an impressive looking Ctrl-Opt-Cmd-8 set to "Reverse Black and White". Obviously I had to play.

In a very straight-forward fashion, it's a shortcut that turns your screen into a negative. The odd part: I like it. I wouldn't object to using those colors for blogdowntown at all. And the UI elements actually work pretty well too.

Perhaps it's not the most useful of functions (for the abled, at least... it is an Accessibility function), but it's an oddly fun way to view the web. It makes you feel like you're in a really high-tech movie, to paraphrase the guy I work next to.