ajayver

This plugin gives you the ability to change the appearance of your RSS feed. You can easily add images from custom fields, read more link, category list, tag list and any custom code before or after the feed items. Also, the plugin allows you to delay feed publication for several minutes. It is helpful, when you made some mistake and you will have time to fix it before the post went to RSS and all other services like facebook or twitter.

RSS Manager

This plugin gives you the ability to change the appearance of your RSS feed.

man_ketan

This plugin allows you show/hide text in post and page by inserting simple shortcode. 
Example usage: [km_showhide]Hidden content goes in here.[/km_showhide]

KM-ShowHide

This simple plugin allows you to toggle your content inside shortcode.

RSS Manager vs KM-ShowHide