Zane Matthew

This plugin places a comment form similar to Facebook, only displaying a single line textarea, which submits when the user presses “enter/return” on their keyboard.
<h4>Features</h4>
<ul>
<li>Single line textarea</li>
<li>Auto expanding textarea</li>
<li>AJAX submitted comments</li>
<li>AJAX loaded comments</li>
<li>Admin settings for additional styling</li>
</ul>

Inline Ajax Comments

Displays a single line textarea for entering comments, users can press "enter/return", and comments are loaded and submitted via AJAX.

webgarb

http://www.youtube.com/watch?v=z49D40Ureao 
Wp Inline Edit will add ability to author/admin/editor to edit post/page from directly from site without going to wp-admin edit page.
Just updated a post in your WordPress Blog, 
but noticed a spelling/grammar error? 
Got more work and less time? 
Aah! You no longer have to visit the edit page again, as with this plugin “Wp Inline Edit”, you can simply double click on your post to edit it from the post itself. It will make “inline editing” a trend that every blogger would embrace.
View the working of this plugin on <a href="http://youtu.be/z49D40Ureao" rel="nofollow ugc">Screencast at Youtube</a> 
Please comment you review about this plugin here <a href="http://webgarb.com/wp-inline-edit/" rel="nofollow ugc">Wp Inline Edit Page</a>.

WP Inline Edit

http://www.youtube.com/watch?v=z49D40Ureao

Inline Ajax Comments vs WP Inline Edit