To give a real world example of how true this is, I have a friend that owns a service company. He subscribes to Visistat for which he embeds a small snippet of Javascript into every page in his site. He uses a product of theirs called LeadCaster which then identifies the company name and often the contact name of people that visit the site. How does it do this? Look at Visitstat's Learning Center for an explanation:

NOTE: Contact information is supplied by the contact databases of Data.com (formerly Jigsaw), NetProspex and LinkedIn. Not all information will be available for every company and listing, however, your reports will show all the data we are able to access for you.

So for a real world example that he told me about a few hours ago, a lady was on his website. She left without doing anything more than viewing a few pages. Through Visistat, he was able to get her company name and contact information from LinkedIn. He looked up the phone number for her company and called her. He then said, "I understand you're interest in ..." She replied, "How did you know I am interested in ...?"

This is spooky as shit and almost made me delete my LinkedIn profile today.