Peter Westwood

This plugin allows you to specify a specifc excerpt for WordPress pages.
The plugin adds an extra box to the set an Optional Excerpt for a WordPress page similar to the box which is available for posts. The box is aded using the dbx_page_advanced hook for versions of WordPress earlier than 2.5 and using add_meta_box() for WordPress 2.5 and later.

PJW Page Excerpt

This plugin allows you to specify a specifc excerpt for WordPress pages.

Marcus Downing

Zaybiz

A simple plugin to enhance your use of the_excerpt() function. Allows you to change the default title and description of the excerpt box, add an excerpt box to pages and show a customizable jQuery character counter with the ability to limit the amount of characters.
The jQuery character counter from <a href="http://tomdeater.com/" rel="nofollow ugc">Tom Deater</a> provides a user friendly way to limit the amount of characters while writing.

Excerpt Tools

Change the default text and description of the excerpt box, add an excerpt box to pages and show a jQuery character counter and limiter.

PJW Page Excerpt vs Excerpt Tools