asimeon

Costumizable search widget. Shows the search results dynamic on your sidebar.
Features:
<ul>
<li>Show or don’t show a searchfield or configure another input field</li>
<li>Configure the search: post type, categories, tags, post title and content</li>
</ul>

Dynamic Search Widget

Shambhu Patnaik

Category Wise Search Widget plugin.You have option search specific category content.
Features
<ul>
<li>Search post category wise.</li>
<li>Set default category.</li>
<li>Exclude categories in search category field.</li>
<li>Exclude categories with child in search category field.</li>
</ul>
More detail : http://socialcms.wordpress.com/

Category Wise Search

Category Wise Search Widget plugin.You have option search specific category content.

Dynamic Search Widget vs Category Wise Search