Google+ API functionality.
https://developers.google.com/+/
Widgets
Get access to data on 7,423,227 websites that are Google Plus One Platform Customers. We know of 1,807,412 live websites using Google Plus One Platform and an additional 5,615,815 sites that used Google Plus One Platform historically and 957,141 websites in the United States.
Get a list of 7,423,227 websites using Google Plus One Platform which includes location information, hosting data, contact details, 1,807,412 currently live websites and an additional 737,408 domains that redirect to sites in this list. 5,615,815 sites that used this technology previously and 957,141 websites in the United States currently using Google Plus One Platform.