Yudhistira Mauris

This plugin makes it easier for your website visitors to link back to your website by displaying a badge and HTML code box as a widget. Your website visitors only need to copy the HTML code inside the HTML code box and paste it on their website. Backlinks improve your website off-page SEO and boost your website ranking in search engine.
<h4>How to use this plugin:</h4>
<ol>
<li>Install and activate the plugin.</li>
<li>On Appearance -> Widgets, drag and drop the widget to sidebar or other widgetized area.</li>
<li>Fill in the required fields.</li>
</ol>

Link Back Badge Widget

Displays a badge and an HTML code box as a widget to ease your site visitor linking back to your website.

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

Link Back Badge Widget vs WP-TopScoredCommentAuthors