2 usefull form alters (D6)

A very common and hard-to-nail task is to remove the "Preview" and "Split Summary At Cursor" buttons from drupal forms, this simple form alter will do just that :

function MODULENAME_form_alter(&$form, $form_state, $form_id) {

  // Remove the "Preview" button (sitewide) from comment form
  unset($form['preview']);
  // From node form
  unset($form['buttons']['preview']);

  // Removing the "Split Summary At Cursor"
  $form['body_field']['teaser_include']['#access'] = FALSE;

}