jgwhite33

Allows you to insert a listing of related Amazon products, on the single post page by using a custom field called amazon_search and inserting simple code in your template file. 
The listings are completely customizable according to parameters defined in the admin panel. If you include an Amazon Associate ID, you can even earn commission! Also allows you to share revenue with your authors on a multi-author blog. Whoever wrote the post gets credit in the listings. Creates a custom field on the author profile pages so they can input their campaign ID. Whoever wrote the post gets credit in the listing.
A few of the features:
<ul>
<li>Specify the search with a custom field in the post called amazon_search</li>
<li>Allows you to use the Amazon Associate Network</li>
<li>Allows multi-author blogs to share revenue, you can even specify the percentage to share</li>
<li>Can share revenue with the author of the post if you desire</li>
<li>Uses advanced search parameters</li>
<li>Display is easily customizable</li>
<li>Hides the affiliate link to Amazon</li>
</ul>

WP Amazon Ads

WP Amazon Ads - allows you to easily insert Amazon product listings into your WP posts, and earn commission from sales.

mattdu

This plugin uses the custom taxonomy features of WordPress to create “bylines” — essentially, tags representing authors who contributed to a post. The differentiating feature of this plugin is that it should not require any modifications to your theme files (assuming it is already displaying the post author).
This plugin would be useful for publishing situations where the majority of your content is from contributors who you don’t necessarily want to have access to your back-end. It still conveys the appearance that the authors are members of the site (it provides a built-in archive page for each Byline). If your theme displays tag descriptions, you could use the Byline description field to identify guests vs. “staff” writers or provide other author information.
You can see an example of this plugin at work at http://thedailycougar.com

Byline

The Byline plugin is simple and suitable for multi-author WordPress sites.

Best For Multi Author

Solves the co/multi-author problem without modifying the theme. Uses a custom taxonomy, "Byline," that replaces the Display Author.

WP Amazon Ads vs Byline