Add to All is a powerful plugin that will allow you to add custom code or CSS to your header, footer, content or feed.
Close comments, pingbacks and trackbacks on your post automatically at intervals set by you
Display a list of contextually related posts for the current post. You can select the number of posts to display and if you want to automatically display the related posts in your content / feed.
Anonymously track your visitors and display popular posts on your WordPress blog.
This plugin will show “Readers who viewed this page, also viewed” links on your page. This is similar to Amazon’s product pages which state “Readers who have bought this, also bought”.