Stackoverflow. Its closest competitor, experts exchange, was a slow website that required you sign up to see an answer that was rarely useful. There's a direct correlation to SO and dollars of revenue I've driven.
I believe Google penalised them for doing it so they used another sneaky trick where they showed a obscured/pixelated answer first and then the actual one further down than most people would scroll.
SO was better in every way.
This might make someone here angry that they weren't aware of it (or make them smile):
This is how they did it:
The answers were always visible if you just scrolled far enough down the page.
At least that is how I experienced it - and I thought every oldtimer knew! :-)
There's a full description of how it worked on their Wikipedia article.
https://en.wikipedia.org/wiki/Experts_Exchange#Paywall
You should probably check before dishing out patronising and incorrect answers.
Somewhere out there must be an RFC that discusses the original thought process behind designing for case sensitive vs case insensitive domain names, or why domains should be case insensitive while URL paths should be case sensitive... Ironically this SO post seems to be a decent starting point for my curiosity: https://stackoverflow.com/questions/7996919/should-url-be-ca...
Let's not even mention the plant nursery on the Mole River which ended up with www.molestationnursery.com ...