The co-registration method of lead generation occurs on a third party website. For example during the sign up process you are given the option to tick a box and sign up for numerous other offers and websites. The visitor never actually visits your website; instead you are sent their details to contact them directly. Because you do not directly interact with the lead, fake sign ups and "gaming" the system using names and addresses from the phone book is not as unusual a practise as you would hope.
Lead nurturing is the path to higher ROI and better results. It is the process of converting contacts in your database into buyers . . . more about lead nurturing
Case studies showing how lead generation has helped other business, and how it can help yours too . . . see our case studies