Plugin for WordPress: Adds a 'admin_parse_output' hook to allow you to parse and modify the HTML generated by the admin.

admin-parse-output.php

<?php
/*
Plugin Name: Admin Parse Output
Description: Adds a 'admin_parse_output' hook to allow you to parse and modify the HTML generated by the admin when other hooks are not available. Starts HTML capture with the 'admin_init' hook and ends with the 'admin_footer' hook so it will miss anything that comes after 'admin_footer' (see the last lines of /wp-admin/admin-footer.php to see what this hook will miss.)
Version: 0.1
Author: Mike Schinkel
Author URI: http://mikeschinkel.com
Notes: Written for http://lists.automattic.com/pipermail/wp-hackers/2010-November/036150.html
Example Usage: See https://gist.github.com/717515
*/

if (!class_exists('Admin_Parse_Output')) {
	class Admin_Parse_Output {
		static function on_load() {
			add_action('admin_init',array(__CLASS__,'admin_init'),1000);
			add_action('admin_footer',array(__CLASS__,'admin_footer'),1000);
		}
		static function admin_init() {
			if (has_action('admin_parse_output')) {
				ob_start();
			}
		}
		static function admin_footer() {
			if (has_action('admin_parse_output')) {
				$html = ob_get_clean();
				$html = apply_filters('admin_parse_output',$html);
		    echo $html;
			}
		}
	}
}
Admin_Parse_Output::on_load();