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?

Boone Gorges

If you install BuddyPress on an already thriving WordPress installation, you’ll notice that existing blog comments and posts are not inserted into the activity stream. This plugin fixes that.
Requires WordPress Multisite

BP Import Blog Activity

Updates BuddyPress activity streams with missing blog comments and posts

Kittens for Comments vs BP Import Blog Activity