A simple sidebar widget displaying your most viewed content.
You can find a post or page's ID number by going to the main listing of posts or pages, and hovering over the title. You will see a link with a value of the ID in it such as "post=154".
You need to check the box and ensure that you click "Save" to remove the statistics (reset to 0). You then have to uncheck the box and click "Save" again to restart collecting view data.