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.

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.

Excerpt character limiter vs PJW Page Excerpt