To help you find your next car.  If you think for a minute about the network of people around you including friends, family, and co workers it is pretty huge.  Now contemplate how many people that those people know, and those people know, etc.  There are a lot of people that you could potentially be put in contact with to help you find cheap cars that are for sale.  At any given moment, there are millions of cars for sale around the country, and your chances are really good that some of those cars are in your direct network of friends, or your extended network.  Your secretary’s cousins best friend may have the car of your dreams for the price you have been dreaming about, but they will never know unless you start talking about it.