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.

Vishit Shah

This is very simple plugin to remove extra p and br tags in post and page editer
This plugin remove extra p and br tags from the_content, the_excerpt and widget_text_content.

Remove Blank P Tag

This plugin remove extra p and br tags from the_content and the_excerpt.

PJW Page Excerpt vs Remove Blank P Tag