mc2w

This plugin creates a form with a drop down list that allows your users to search through specific categories. It allows you to choose which categories appear in the dropdown and which ones do not.
<h3>Things To Do</h3>
<ul>
<li>Make the plugin call upon a css folders, so users can design the plugin through css</li>
<li>Handle errors involving rare situations</li>
</ul>
Make some suggestions and I’ll see what I can do!

Super Search

Generates a drop-down list and a text box to allow your visitors to search for posts within specific categories.

Creato

Superfast Search is a search box plugin that will display your search results instantly as you type.
It comes with an easy to use Widget as well as a Shortcode.
See http://superfastsearch.co.uk/ for a guide, examples and demos.

Superfast Search Basic

The easy to use results-as-you-type search box.  Widget and shortcode.

Super Search vs Superfast Search Basic