Some site

Millions of domains are registered every year and a large proportion of these domain names are never developed into websites. They remain parked, using displaying pay per click (PPC) advertisements. When a visitor to the domain name, clicks on one of the advertising links, the owner of the domain name is credited for the same.

Over the last year, the revenue from the parked domain names has reduced by more than 50% in many cases. while this is partly due to the recessionary economic conditions in many countries, many of the advertising feed providers like Google have also reduced the amount they pay. Since they now have an option, many advertisers opt out of advertising on the parked domain.