Will Brubaker

You’ve poured your heart and soul in to writing fascinating blog posts.  You know you have a lot of readership, but nobody except your mom is leaving comments.  That’s a bit discouraging right?  Entice your readers to leave comments by giving them a picture of a cute kitten in return.
Just prior to the comment form coming in to view, an unobtrusive panel will be displayed with a short message that says: “Your comments make us happy.  Leave a comment, get a kitten!”
 
When a comment is submitted, a picture of an adorable kitten is displayed in a modal window.
Caveats:
This plugin assumes that your comment form is A) built with the ‘comment_form’ WordPress function and B) that your comment form has an id of “commentform” (This is the WordPress default, but your theme developer may have changed the behavior for whatever reason. 
This plugin assumes that comment forms only appear on single posts and only loads the code when a single post (or page) is loaded. 
 
<h3>Other Information</h3>
I created this plugin for my own amusement and am offering it for you to use as you wish.  If you find it useful but would like more features, please do ask.

Kittens for Comments

Works well, customizable and just damn cute! Love it. =D



Awesome

Encourages your readers to leave comments with the promise of a kitten picture.  Who doesn't love kittens?

BlogFollow is a WordPress pluggin that shows a snippet from a commenter?s blog at the bottom on their comment. The purpose of this is to encourage user participation in your blog, by providing an incentive – an excerpt from their blog. Both parties win. The blog using BlogFollow receives more comments/content. The commenter has a chance to win new readers using both the comment and a snippet from their blog, which may be completely unrelated to the post topic.

BlogFollow

BlogFollow is a WordPress pluggin that shows a snippet from a commenter's blog at the bottom on their comment.

Kittens for Comments vs BlogFollow