There are lots of companies that are selling lead generation systems. Basically, they say they can tie website visitors to companies, identify corporate decision makers at these companies ( I assume by digging into Hoover or Jigsaw with their API), and putting them in a CRM system.
My question is: how do you know which IP goes to which company? Are there companies putting this kind of data together? I guess it would be easy if a reverse lookup for a visitor is from foo-23-42.barbaz.com, but otherwise, is there a way good way to do it?