Ever wondered how many people read a particular post? (keeping in mind the traffic) Well, there is a wordpress plugin by AlexKing that does the job. What it does is, keeps track of activity on your blog and calculates a popularity percentage for each post and page.
Since page view counts, etc. are cumulative, newer posts will generally have lower popularity values than older posts. This, of course, evens out over time.
The values for different events (page views, feed views, comments, etc.) are configurable on a per-site basis, so each site may rank their content differently.
The Popularity Contest plugin is available on my WordPress Pluginspage.