This post introduced me to a concept I had never seen before.

Not the content though. Instead I'm referring to some new web chicanery with the janky popup that appears when you mouse your mouse off the page in preparation for navigating back.

Normally these just invite you to join an email list or whatever.

But this one seems to be actually personalized based on referer - I saw "Sorry to do this to you HN.". I had instinctively closed it as always before it struck me this is the first time I've ever seen that.

I guess there's some kind of database somewhere of referers, with a groovy customized "sorry you're leaving" phrase for each one?