Google+ API functionality.
https://developers.google.com/+/
Widgets
Get access to data on 7,591,468 websites that are Google Plus One Platform Customers. We know of 1,200,023 live websites using Google Plus One Platform and an additional 6,391,445 sites that used Google Plus One Platform historically and 654,837 websites in the United States.
Get a list of 7,591,468 websites using Google Plus One Platform which includes location information, hosting data, contact details, 1,200,023 currently live websites and an additional 496,887 domains that redirect to sites in this list. 6,391,445 sites that used this technology previously and 654,837 websites in the United States currently using Google Plus One Platform.