As Anika Mae says, every domain has some level of contact details available in response to a 'whois' query, but whois.com is a domain registrar and wannabe repository for people's various online identities.
Ironically, they use a service which conceals their contact data in the domain's 'whois' information, but are happy to show their faces on the site - apparently they're a small bunch of people from Singapore.
How often are you getting them on your visitor info?