A content farm (or content mill) is a website that provides limited pay to large numbers of writers to generate a wide range of (user-generated) content which is often specifically designed to maximize page views in order to generate advertising revenue. For a more in-depth explanation of content farms, see Content Farms on the Web (from Santa Rosa Junior College.) 

Who writes for content farms and how much do they get paid?

Some examples of content farms are:

 

See a N.Y. Times cartoon on content farms.