P. Chandra

Adds copyright notice at end of articles in full text RSS feeds, with back links to the blog and original article.
A notice gets attached at the bottom of feed articles like this 
Original Article: Title of Article (linked to permalink) 
Copyright Year. Blog Title (linked). All Rights Reserved
Your Blog title is linked to your blog Url. Your article title is linked to the article permalink.
Blog copyright notices are important as your feed gets freely distributed across the web and is republished without permission by RSS scrappers and autoblogs. After using this plugin, now RSS scrappers will link back to your site, which will suggest to search engines that your blog and article was the original source.

Simple Feed Copyright

Adds copyright notice at end of articles in full text RSS feeds, with back links to the blog and original article.

mortenf

This plugin monitors a <a href="http://www.intertwingly.net/code/venus/" title="Planet Venus" rel="nofollow ugc">Planet Venus</a> cache 
directory and syndicates new entries as posts. 
It automagically creates users and categories as necessary.
The plugin was originally released on <a href="http://www.wasab.dk/morten/blog/archives/2006/10/22/wp-venus" title="WP: Venus" rel="nofollow ugc">Binary Relations</a> by <a href="http://www.wasab.dk/morten/" rel="nofollow ugc">Morten Frederiksen</a>.
<h3>Maintenance</h3>
When running correctly, the WordPress Venus plugin automatically adds users, categories and posts as needed, based on the information in the Atom entry files from the Venus cache directory. Each Atom entry file is only parsed when created or updated, so you may update existing posts, categories and users in WordPress as needed, in case something looks odd — your changes will not be overwritten unless the entry file is updated. If you delete a post, the plugin will try to remove the corresponding Atom entry file in the cache directory as well. For that to work, the web server process needs write permission to the cache directory.
If you find that the same users suddenly appears more than once in the WordPress user system (this may happen if the same user posts from different sources), you can use the Venus options screen to merge the two into one. The merge will be preserved for future arriving posts. This is accomplished by storing unique IDs for each user, as can be seen and maintained on the user edit screen.
Since the plugin scans the Venus cache directory to look for updates, you will likely find, that it slows down after a while. You may want to clean out the cache directory every now and then, possibly through the use of a cron job, and Venus’s -x switch.
<h3>License</h3>
Copyright (c) 2006-2009 Morten Høybye Frederiksen <a href="mailto:morten@wasab.dk" rel="nofollow ugc">morten@wasab.dk</a>
Permission to use, copy, modify, and distribute this software for any 
purpose with or without fee is hereby granted, provided that the above 
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES 
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

WP-Venus

A plugin for running a syndication planet using Planet Venus through its cache directory, with complete support for multi author feeds and categories.

Simple Feed Copyright vs WP-Venus