Here's my Google story. I was planning a trip to a remote mountain town, to completely separate from all the big tech giants. So I went online to review the map to the cabin we'd rented...
And Google added a pushpin to the cabin where I was staying, along with the dates for the entirety of my stay.
They'd scanned my Gmail inbox, found the reservation, extracted the dates and location, and then waited until I went to Google Maps for driving directions.
There's a way to turn off some of this -- which I immediately hunted down and activated. But it still bothers me that I didn't know it was on by default.