Androfire

<p>TDisplays links from del.icio.us, Technorati, Reddit, Digg and TailRank that is relevant to the current category of your blog. Eg: Your visitor browses the ?humor? category of your blog; the links will come from ?http://del.icio.us/tags/humor? and so on. This means that you do not have to change any code for each specific category.</p>


WP-ExternalFeed

Displays links from del.icio.us, Technorati, Reddit, Digg and TailRank that is relevant to the current category of your blog

ladislav.soukup

<p>You can improve the default WordPress RSS feed to include:</p>
<ul>
<li>This plugin will add post thumbnail to RSS feed as “media:content” and “enclosure” tags.</li>
<li>Image is also added to HTML part of “description” and “content:encoded” tags.</li>
<li>You can also add server signature to end of feed content in form “Source: XYZ”.</li>
<li>Inject advertisement (image with link) after nth paragraph of each post.</li>
</ul>
<h4>Post thumbnail</h4>
<p>Add post thumnail to each post’s excerpt and full text (if enabled in WordPress configuration).<br />
Image will be added just before text of each post in RSS feed.<br />
Post thumbnail is also added as media:content and enclosure tag to RSS feed.</p>
<h4>Full-text RSS Feed when accessed via special URL</h4>
<p>You can access RSS Feed with full content posts even when WordPress is set to RSS “Excerpt only” mode. Just setup a “secret key” and enable the override…<br />
You can then request feed url with special query param ?fsk= to override “excerpt only” mode to “fulltext” mode. This is great for services like Google Currents.</p>
<h4>Server signature</h4>
<p>You can add server signature just after the full text content of post to each RSS post.</p>
<h4>ADs</h4>
<p>Very simple implementation of advertisement to each RSS feed post item. Ad is a simple clickable image (stretched to 90% of width – maximum of 700px).<br />
There is no click monitoring, so you should use something like bit.ly to track clicks.</p>
<h4>Support</h4>
<p>Please, if you need support or help, visit: https://bitbucket.org/ladasoukup/sb-rss-feed-plus/issues</p>
<h4>Translatable</h4>
<p>All text can be translated using standart language files, text domain is: “SB_RSS_feed_plus”.</p>
<p>Included translations:</p>
<ul>
<li>English (default)</li>
<li>Czech</li>
</ul>


SB RSS feed plus

In the code there are various settings that would allow you to toggle adding the RSS image to content and excerpt and so on, but they don't appear.

The settings page is blank of any actual settings...

https://s3-us-west-2.amazonaws.com/elasticbeanstalk-us-west-2-868470985522/ShareX/2017/11/chrome_2017-11-01_22-31-15.png

You can't even customize the image size in the feed, and a support thread asking how to do so is still unanswered. I think this plugin is abandoned.

Settings don't work

This plugin will add post thumbnail to RSS feed items. Add signatur or simple ads. Create fulltext RSS (via special url).

WP-ExternalFeed vs SB RSS feed plus