This plugin adds Spotlight ™ like live search with an ajax popup to 
the default search box. See the screenshot.
It can be used as a widget or directly as a PHP call in the theme.
The Live Search Plugin is heavily based on John Nunemaker’s 
<a href="http://www.wp-plugins-db.org/plugin/addicted-to-live-search/" rel="nofollow ugc">Addicted To Live Search</a>.
<h4>Changelog</h4>
<ul>
<li>1.4.7 Fix by Tony for “With mouseover on result in IE, there is no background image or color”.</li>
<li>1.4.6 Added livesearchpopup_resultsbox(width) to put the popup below a search box of your choice, e.g. from a theme.</li>
<li>1.4.5 Do not initialize if no livesearchpopup_results is found. In contrast to the original live search this plugin does not make sense without the popup anyway. This fixes a JavaScript bug in IE7.</li>
<li>1.4.4 Use wpurl instead of siteurl to allow installations of WordPress at different addresses (thanks to Draco)</li>
<li>1.4.3 Use <?php instead of <? in live-search-popup.php</li>
<li>1.4.2 Force update script to update the plugin.</li>
<li>1.4.1 Switched to the_post instead of the deprecated wp_start().</li>
<li>1.4 Finally permalinks work together with this plugin. In addition a “Show all” links was added at the bottom for the case that there are more posts than shown in the popup (thanks to Marco Luthe).</li>
<li>1.3.4 Moved the placeholder and autocomplete attributes of the search box to JavaScript as they are not XHTML valid (thanks to Marco Luthe)</li>
<li>1.3.3 Added some print commands in front of get_bloginfos (thanks to upekshapriya who noticed that)</li>
<li>1.3.2 Force update script to update the plugin.</li>
<li>1.3.1 Relative paths in css to allow installation which are not at the domain root.</li>
<li>1.3 Fixed behaviour for change and blur events of the search box. This fixes the “click-through” bug.</li>
<li>1.2.1 Updated to reflect that it works with 2.3 as well.</li>
<li>1.2 Bugfixes</li>
<li>1.1 Bugfixes</li>
<li>1.0 First release</li>
</ul>

Live Search Popup

Spotlight (tm) like live search with an ajax popup

Alkaweb

Add to your site a top-notch live search field.
Eonet Live Search can be added to any search field. 
It’ll create a nice popup box with the search’s result in real time. It plays very well with Buddypress, Woocommerce 
and any other custom post type. Specific integration can be added by us.
<a href="http://alka-web.com/eonet/live-search/" rel="nofollow ugc">Live Demo</a>
<h4>Featured features:</h4>
<ul>
<li>Options panel</li>
<li>Buddypress Members integration</li>
<li>Buddypress Groups integration</li>
<li>Buddypress Activities integration</li>
<li>Works with any custom post types</li>
<li>Pages / Posts integration</li>
<li>AJAX powered, no page reload</li>
<li>User search history</li>
<li>Options to restrain the search sections</li>
<li>Results listed within organized tabs</li>
</ul>
<h4>For developers:</h4>
<ul>
<li>Hooks/Filters available in all the plugin code</li>
<li>Minified files</li>
<li>Documented code</li>
<li>GPL license</li>
<li>Secure development using tokens and WordPress native functions</li>
</ul>
If you’re looking for a next generation live search plugin, you should give it a go!
We’re open to any feature suggestion.
This plugin has been developed as a side project by the Alkaweb developers team.

Eonet Live Search

It's an useful and pretty flexible plugin!

I like it

Search dynamically in real time through all your site, including pages, posts, members, products & so on.

Live Search Popup vs Eonet Live Search