Can I add more option to "Publishing options" ?

I don't know of a way of extending the Publishing options list, but you could do this by creating another taxonomy and using that in Views2.

Actually getting the option onto the form is very simple in Drupal 6. In a custom module, you can do this:

function mymodule_form_alter(&$form, $form_state, $form_id) {
  if($form_id == 'my_content_type_form') {
    $form['options']['super_special'] = array(
      '#type' => 'checkbox',
      '#title' => t('This is a Super Special Magic Node'),
      '#default_value' => 0,
    );
  }
}

But of course, this data won't be held anywhere after you submit it, so you will also need to build a way to capture it and store it somewhere. For instance, in a CCK field. To capture it, you can do this:

function mymodule_nodeapi(&$node, $op) {
  switch($op) {
    case 'presave' :
      if($node->type == 'my_content_type') {
        $node->field_super_special = array(
          array('value' => $node->super_special),
        );
      }
      break;
  }
}

Then to catch it and set the checkbox the next time the form gets edited, we need to make a few modifications to form_alter. Here is the finished version:

function mymodule_form_alter(&$form, $form_state, $form_id) {
  if($form_id == 'my_content_type_form') {
    $x = node_load(arg(1));
    $specialvalue = $x->field_super_special[0]['value'];
    $form['options']['super_special'] = array(
      '#type' => 'checkbox',
      '#title' => t('This is a Super Special Magic Node'),
      '#default_value' => $specialvalue,
    );
  }
}

If you do this, you will probably want to suppress the display of the real CCK field, either by using the content_permissions module or adding more lines to form_alter, or just use CSS (display: none;).

Alternately, you could save the data in a table of your own, as long as you pull it back up when you load the form again (again, this would be in form_alter).

Obviously the details will differ for every site, but this should be enough to get you started.

http://drupal.org/project/flag

https://drupal.org/project/custom_pub