luzifer

This plugin is a replacement for the default “Top Ten Comments” because that plugin did not really do 
what I wanted. In the default plugin shows ten people who gave the most comments ever. But if an author left 500 comments two years ago and left the page for ever after this he would show up at the top 
position until another author would reach more than 500 comments.
In this plugin the top commenters score is calculated by using the time left since a comment and also 
the number of comments. So the author mentioned in first paragraph would slowly move out of the 
toplist and other comment authors posting more recently will get a chance to show up in the list.

WP-TopScoredCommentAuthors

This Widget shows your Top-Comment-Authors based on a score calculated from comment-age and frequency

PowieT

This widget plugin will display a backlink to the parent page at the end of subpages
<ul>
<li>Only on subpages</li>
<li>at the end of the page</li>
<li>link to the parent page</li>
</ul>

Parent Page Link

This widget plugin will display a backlink to the parent page at the end of subpages

WP-TopScoredCommentAuthors vs Parent Page Link