Luis A. Ochoa

Exclude Page and Attachment post types from search results.
<ul>
<li>Very fast execution</li>
<li>No configuration required</li>
</ul>

Exclude From Search

Exclude Page and Attachment post types from search results.

Michael Adams (mdawaffe)

Just One Category will cause WordPress to display on a category archive page 
only those posts which are direct members of that category, i.e. this plugin 
will exclude from that category page all posts which belong to any of that 
category’s subcategories but do not belong to the category itself.

Just One Category

On a category's archive page, displays only the posts directly in that category, not in any sub-categories.

Exclude From Search vs Just One Category