Joen Asmussen

This plugin appends a customizable message with a link to every post in your RSS feed. This can help discourage robots from scraping your content (automatically copying and posting it elsewhere). This is the default message:
<pre><code>[postname] originally appeared on [sitename] on [postdate].
</code></pre>

Anti Feed-Scraper Message

Discourage robots from scraping your RSS feed.

alaingg

Simple plugin that allows to include the images into your wordpress rss, rss2. 
The plugin use the post/page thumbnail or the firt attached image to the post/page gallery. viste the <a href="http://web-argument.com/2008/11/09/wp-rss-images-wordpress-plugin/" rel="nofollow ugc">plugin page</a> for details.

Anti Feed-Scraper Message vs WP RSS Images