darrinb

Generates a template tag that allows you to easily display a snapshot of text. 
Useful for meta descriptions, post snippets, or your own custom block of text. 
Displays a snippet of text without having to use the <–!more–> quicktag.

WP Snapshot

Easily display a summary of post text or custom text.

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.

WP Snapshot vs RSS Manager