The Vote It Up plugin enables visitors to vote for and against posts.
Note: Version 1.2.x has been re-classified as unstable pending recent issues with the plugin by several users. Version 1.1.1 is the current stable version
This plugin adds voting functionality for posts. This function is similar to Reddit or Digg, in that visitors can vote for and against.
Guests can also vote for posts. This functionality can be disabled as well.
A widget can be displayed showing the most voted posts on your blog, giving further exposure to your popular posts.
A brief summary of what the plugin has to offer: