This plugin allows your visitors to simply like/recommend your posts instead of comment it.
You can download it from http://wordpress.org/extend/plugins/i-recommend-this/
This plugin is based on Benoit "LeBen" Burgener "I Like This" Plugin and has been modified after getting requests for the changes I had made on my website.
This plugin include
A counter/button to display the number of "like" and to vote.
A widget and a function to display the X most liked posts.
A preference pane with some options.