Pligg is an open source CMS (Content Management System) designed to mimic the functionality of [Digg] using Web 2.0-style techniques. It allows the creation of social networks for your visitors along with a community feedback network. Pligg's official website states the following:
"Members can publish content and cast their vote on articles and comments, pushing the most appropriate content to the top of the site. Pligg’s emphasis on voting for the best content promotes the most popular content on your website."
Pligg's website features a blog, a forum and online documentation for where you can get more details about the application.