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

sunnyverma1984

Backlinks are crucial to SEO. Google gives more importance to website that have higher number of quality backlinks. 
A website with good amount of backlinks will get higher position in SERP.
Backlink Checker Plugin helps blogger to find list of webpages pointing their blog using anchor tag. 
This plugin also shows anchor text and type of backlink (doFollow or noFollow).
This plugin uses free MOZ API to generate backlink report. 
To use this plugin you have to get free <a href="https://moz.com/community/join" rel="nofollow ugc">moz account</a> with <a href="https://moz.com/products/api" rel="nofollow ugc">API access</a>.

Backlink Checker

Get the list of backlinks pointing to your blog

WP-TopScoredCommentAuthors vs Backlink Checker