The most obvious are Google Payments (from the merchant side), Google Analytics, Google Ads (doubleclick). Then there's street view cars collecting photos and wifi data, Google registry services siphoning up domain metadata, and of course any information someone else enters about you- if they save their contacts to google and it includes you, you're suddenly part of their graph.
Then there's the direct cell phone tracking-
> Investigators who spoke with The New York Times said they had not sent geofence warrants to companies other than Google, and Apple said it did not have the ability to perform those searches. Google would not provide details on Sensorvault, but Aaron Edens, an intelligence analyst with the sheriff’s office in San Mateo County, Calif., who has examined data from hundreds of phones, said most Android devices and some iPhones he had seen had this data available from Google.
Don't forget about GMail. Everytime you send a mail to somebody on GMail, which might not be obvious with custom domains, your mail will be analyzed by Google. And your email address serves as the perfect ID.
Small note, but can't you block Google Analytics with something like Privacy Badger? Google Payments and Google registry services seem near impossible to avoid though. Not to mention the near requirement to use certain Google products in certain lines of work.
This is the main inescapable one for me. I have uMatrix to block analytics and all that, but so many websites simply wont work without recaptcha.
My solution lately has been to feed them junk data until they either give up on me or erroneously perceive my input as non-erroneous (not sure which it is). Takes some time, but to me it’s worth it. If we can get enough people doing this they might have to get rid of it all together. (Vastly unlikely, but a guy can dream, right?)
Then there's the direct cell phone tracking-
> Investigators who spoke with The New York Times said they had not sent geofence warrants to companies other than Google, and Apple said it did not have the ability to perform those searches. Google would not provide details on Sensorvault, but Aaron Edens, an intelligence analyst with the sheriff’s office in San Mateo County, Calif., who has examined data from hundreds of phones, said most Android devices and some iPhones he had seen had this data available from Google.