Comment Rating is a simple plugin which lets readers like or dislike comments. It works the same way that Facebook likes works.
For such a basic plugin, it lets you customise how it works in many ways. Poorly, highly and hot comments can all be set by choosing a value. You can also change the thumbs up and down image, position the image above or below the comment area and even make it so that only likes or dislikes are used.
Once you have installed the plugin you will see a like and dislike option with every comment. In articles with lots of comments, this will allow you to quickly see the best comments on the page.
A simple plugin but one which adds a useful feature to your comment area. If you are looking for a way for your readers to rank your comments, I recommend checking it out.
Link: Comment Rating