This plugin will integrate AJAX commenting feature into your WordPress Blog. It uses the powerful JavaScript Framework jQuery to handle AJAX requests and jQuery Validation plugin by bassitance.de to validate comment form on the client side.
<h4>Feature Summary</h4>
<ul>
<li>Enable AJAX Commenting</li>
<li>Client Side Form Validation</li>
<li>Easily rolls back if JS disabled</li>
<li>Easily configure custom styles for messages</li>
</ul>
<a href="http://webdeveloperplus.com/wordpress/new-wordpress-plugin-wdp-ajax-comments/" rel="nofollow ugc">See plugin page for more details</a>

WDP AJAX Comments

This plugin will enable AJAX comment posting on your WordPress blog.

Jupitercow

This plugin was completely rebuilt from the ground up on August 21, 2012. It now works using the placeholder attribute.
This plugin adds an options page to change the default text that shows in a search field. If your theme’s search input already uses a placeholder, this will change it. If your theme does not use a placeholder, this will add one with javascript. It also adds IE support for the placeholder attribute. Default text will start showing up in IE once you activate this plugin.
Enhanced Search Box Benefits
<ul>
<li>Allows control over the default search box text from the WordPress Admin</li>
<li>Uses modern HTML5 placeholder attribute</li>
<li>ADDS PLACEHOLDER SUPPORT FOR IE!</li>
</ul>

Enhanced Search Box

Add extra functionality to default search box using jQuery.

WDP AJAX Comments vs Enhanced Search Box