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.