The outbrain widget is free and very simple to install. After the one click install process (on most blog platforms), you will see a 5-star rating widget located at the bottom of each post you publish.
NOTE: The widget is only available for the installed version, and not for blogs hosted on Wordpress.com (yet). If your blog is on Wordpress.com, you can help us get approved there by giving your voice.

Get rating & recommendations widget for Wordpress