Is there a plugin that will override the “Error establishing a database connection” message? [closed]

http://yoast.com/custom-wordpress-database-error-pages/

You can make your own Database Error page by adding a db-error.php to your wp-content folder (/wp-content/db-error.php). You can find a good example of such a page in the link above. Don’t forget adding header("HTTP/1.0 500 Internal Server Error"); in that file so it get a proper header message.