This plugin adds up to four new buttons / links to the WordPress Editor panel. You can select to add a quicktag to easily insert: 
Amazon item links 
Amazon product searches 
custom span class 
custom div class
The settings pane allows you to enter defaults, as well as your own Amazon associate ID.

David’s Ultra Quicktags

Adds new buttons to the Editor window (Amazon Links, Amazon Search, etc.).

gozerstudio

<a href="https://github.com/doginthehat/postinpost" rel="nofollow ugc">Post In Post</a> provides an interface to import posts in other posts
Requires PHP 5.2 or higher, WordPress 3.3 or higher.
Features:
<ul>
<li>Customisable per post type</li>
<li>Import post content inline or as a shortcode</li>
<li>Import full or excerpt post content</li>
<li>Safety mechanism again infinite nesting of posts.</li>
</ul>

David’s Ultra Quicktags vs Post In Post