VK is an all-purpose tool for finding friends, considered a Russian version of Facebook.
http://vk.com/
JavaScript Libraries and Functions · Social SDK
Get access to data on 845,672 websites that are VK Customers. We know of 286,269 live websites using VK and an additional 559,403 sites that used VK historically and 32,730 websites in the United States.
Get a list of 845,672 websites using VK which includes location information, hosting data, contact details, 286,269 currently live websites and an additional 75,245 domains that redirect to sites in this list. 559,403 sites that used this technology previously and 32,730 websites in the United States currently using VK.