A popular way developers monetize a web site is through lead generation. Leads can either be direct phone calls to a professional business or they can be email contacts to be followed up on. Most lead generation sites will have contact forms or other user inputted areas to capture a visitors contact information so that their initial interest can be utilized by a “closer” (an experienced sales person) who then turns them into a paying customer. Many web sites sell leads to a eager parties willing to buy them while others may benefit only from a percentage of sales generated based on the lead.
Other sites may use affiliate programs to turn leads into sales dynamically through a referral link to another site where the referral link is recorded and on conversion, electronically delivers a commission to the sender. Leads can be valuable to both buyer and seller depending on the industry and agreements.