One of the first few WordPress plugins, which I installed on Webtoolsandtips is Popularity Contest plugin by Alexking.
It is a useful tool to give ratings to individual posts based upon various factors like, most viewed, most commented, feed views etc. There is a weightage factor assigned to each of these parameters and then the overall marking is found out.
The highest ranking post is assigned a popularity percentage of 100% and rest of the posts are assigned popularity percentages in reference to the highest ranked post. You will see the popularity index of each individual post by looking at the end of each post.
This ranking percentage changes dynamically according to each page view. For instance recently, the popularity of one of my post on LinkChecker was 90% and I got this.
Now you may be able to understand that better.
The Popularity Contest plugin is available courtesy of AlexKing at his WordPress Plugins page.