Kodex Posts likes (kodex-posts-likes) free WordPress plugin

The Kodex Posts likes plugin allows your visitors and logged in users to like or dislike your posts, pages, and custom post types.
The AJaX based interface is clean and fully customizable.
The Dislike button is not required, and the buttons labels are editables.
The buttons shows their counter.
Shortcodes are availables for display the buttons on your post content and for the Like counter only.
In the admin interface, columns are showing the actual count, and there is a metabox in the editon page.