If you want that lovely editor (like the one I am writing in right now for this post) to appear in a plugin, here’s how…

$initial_data='What you want to appear in the text box initially';
$settings = array(
		'quicktags' => array('buttons' => 'em,strong,link',),
                'text_area_name'=>'extra_content',//name you want for the textarea
		'quicktags' => true,
		'tinymce' => true
	);
    $id = 'editor-test';//has to be lower case
    wp_editor($initial_data,$id,$settings);

It really is that simple!