matteotrap

WordPress Excerpts should be short, you know.
But when a user writes a lot, you might want to limit the number of characters for the excerpt panel: that’s where the Excerpt Character Limiter plugin comes handy!
It will basically add a character countdown to the panel titlebar, and it will truncate the text when available characters drop to zero. 
Simple but effective!

Excerpt character limiter

It will basically add a character countdown to the panel titlebar, and it will truncate the text when available characters drop to zero.

tepelstreel

The RSS Image Feed doesn’t create a feed of images, but ataches the first image of the post to your feeds. Normally only the content has images showing. With our plugin there will be a clickable image even in the excerpt and in the content there will be only one image instead of all the images of the post. Since version 2.2 it works as a multisite plugin as well.
The plugin was tested up to WP 4.5 It should work with versions down to 2.7 but was never tested on those.

RSS Image Feed

The RSS Image Feed adds the first image of a post to your feeds, even in firefox and even if you only display the excerpt.

Excerpt character limiter vs RSS Image Feed