When a group of websites, similar in content or subject, all repeat the same information to get more traffic on their pages.
Usually this arrives to the point that articles are ripped from the related sites' pages and distributed on other related sites without acknowledging which site published the article first.
The most common case is the riping of memes, images, and vidoes for the same purpose.
Digg, Youtube, and Ebaums World circulate the same content, often leading to fanboy debates on irc, forums, or image boards about which site is better.
Ebaums is such a traffic whore. They put up the same video right after Youtube.