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.

tcloninger

Provides a custom error, using wp_die(), when any type of feed is attempted.
Feature Overview
<ul>
<li>Removal of ALL feeds</li>
<li>Allows for private (more secure) blogs</li>
<li>Works great with the “Private WP” plugin (requires login to view blog)</li>
</ul>
Important Notes
This is my very first plugin. I found it /very/ strange that nobody had done this.

FeedDisabler Plugin

Disables all feeds (rdf, rss, rss2, atom).

Anti Feed-Scraper Message vs FeedDisabler Plugin