Marc Armengou

Adds a button to clear the search field inside the admin area that will save you time and make intensive search usage more convenient.
Works in the search engine for posts, pages, comments, users, media library, categories, tags, plugins and themes.

Clear Internal Search Button

Adds a button in admin area to clear text of search field for posts, pages, comments, users, media, categories, tags, plugins, and themes.

Alex King

Crowd Favorite

A flexible shortcode and lookup tool for creating internal links in post/page content (or anywhere shortcodes are parsed). 
A lookup tool is added to the sidebar of the post edit screen for locating shortcodes for internal posts.
A plugin by <a href="http://crowdfavorite.com" rel="nofollow ugc">Crowd Favorite</a>. We build Big Things with WordPress.

CF Internal Link Shortcode

A flexible shortcode and lookup tool for creating internal links in post/page content (or anywhere shortcodes are parsed).

Clear Internal Search Button vs CF Internal Link Shortcode