Pligg is Web 2.0 Content Management System (CMS) unlike any other existing CMS. Pligg's Web 2.0 user interface gives your visitors a reason to come back to your site by making them decide on the site's content and giving them the chance to social network.
Digg is a technology news website that combines social bookmarking, blogging, RSS, and non-hierarchical editorial control. With digg, users submit stories for review, but rather than allow an editor to decide which stories go on the homepage, the users do