elebail

Creates 4 feeds :
trdf => rdf in theme (template : feed-rdf.php)
trss => rss 1.0 in theme (template : feed-rss.php)
trss2 => rss 2.0 in theme (template : feed-rss2-comments.php and feed-rss2.php)
tatom => atom in theme (template : feed-atom-comments.php and feed-atom.php)
Those feeds look for a feed template into the theme directory. 
If no template is found into the theme directory the feed uses the default wordpress feed template.
This plugin has been tested with WP2.6.5, WP2.8.4 and WPmu2.8.4
<h3>Update Log</h3>
1.0.1 : Performance improovment.
1.0.0 : Test under WP2.6.5, WP 2.8.4, WPmu2.8.4
0.0.1 : plugin initial creation.

Feeds in Theme plugin

moallemi

This wordpress plugin lets your feed visitors write comments directly from your feed and shows each post comments on post feed. There is no need for your feed subscribers to visit your blog post for reading commnets.
Translations
<ul>
<li>Persian – <a href="http://www.moallemi.ir/" rel="nofollow ugc">Reza Moallemi</a></li>
<li>German – <a href="http://www.felix-griewald.de" rel="nofollow ugc">Felix Griewald</a></li>
<li>Polish – <a href="http://www.dworniak.pl/" rel="nofollow ugc">Pawel Dworniak</a></li>
</ul>
What’s New in version 1.2.1
<pre><code>* Added support for wordpress 4.5
</code></pre>

Comments On Feed

This wordpress plugin lets your feed visitors write comments directly from your feed and shows each post comments on post feed item.

Feeds in Theme plugin vs Comments On Feed