jcapshaw

Google released a new way to notify them of duplicate content so that it is not indexed and penalized. http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html
This plugin allows for you to link to another post or your home page from each post or page that is written letting Google know it is duplicate content.
This is a stable version.

Duplicate Content Link

Allows you to tell Google, Yahoo, and MSN if another page is the canonical, real URL to avoid duplicate content penalties.

openplatform

NealMcConachie

The Guardian News Headlines plugin allows you to add live headlines and thumbnails from the Guardian to a sidebar on your site. The text is indexable by search engines, and relevant to a category of your choice. Have a blog about education? Pick that news category to add relevant content to your blog.
Display options:
<ul>
<li>Selectable news category per widget</li>
<li>Number of headlines per widget</li>
<li>Choose between most recent and most viewed articles</li>
</ul>

Guardian News Headlines

Shows the latest headlines from a selectable news category in a sidebar widget. Headlines link to the live article on the Guardian.

Duplicate Content Link vs Guardian News Headlines