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.

Lars Wallenborn

This plugin allows you to easily add “Show more…” links to your site. Just enclose the content to be hidden between <code>[showhide]</code> and <code>[/showhide]</code>. There is no modification to the backend or fancy editor. Hence the code for this plugin is minimal and the plugin should be easy to review for security issues as well not impact performance.

Show/Hide Shortcode

Small and efficient plugin implementing dynamic "Show more..." links. Just use the [showhide] shortcode, there is no addition to the backend.

WP Snapshot vs Show/Hide Shortcode