Body classes for almost everything in Drupal 6

Drupal 6 Body Classes

<?php
function phptemplate_preprocess_page(&$vars, $hook) {
  
  // Classes for body element. Allows advanced theming based on context
  // (home page, node of certain type, etc.)
  $body_classes = array($vars['body_classes']);
  if (!$vars['is_front']) {
    // Add unique classes for each page and website section
    $path = drupal_get_path_alias($_GET['q']);
    list($section, ) = explode('/', $path, 2);
    $body_classes[] = mytheme_id_safe('page-' . $path);
    $body_classes[] = mytheme_id_safe('section-' . $section);
    if (arg(0) == 'node') {
      if (arg(1) == 'add') {
        if ($section == 'node') {
          array_pop($body_classes); // Remove 'section-node'
        }
        $body_classes[] = 'section-node-add'; // Add 'section-node-add'
      }
      elseif (is_numeric(arg(1)) && (arg(2) == 'edit' || arg(2) == 'delete')) {
        if ($section == 'node') {
          array_pop($body_classes); // Remove 'section-node'
        }
        $body_classes[] = 'section-node-' . arg(2); // Add 'section-node-edit' or 'section-node-delete'
      }
    }
  }
  $vars['body_classes'] = implode(' ', $body_classes); // Concatenate with spaces  
}

/**
* Converts a string to a suitable html ID attribute.
*
* - Preceeds initial numeric with 'n' character.
* - Replaces any character except A-Z, numbers, and underscores with dashes.
* - Converts entire string to lowercase.
* - Works for classes too!
*
* @param $string
*   The string
* @return
*   The converted string
*/
function mytheme_id_safe($string) {
  if (is_numeric($string{0})) {
    // If the first character is numeric, add 'n' in front
    $string = 'n'. $string;
  }
  return strtolower(preg_replace('/[^a-zA-Z0-9_-]+/', '-', $string));
}
?>

Modified from the Zen base theme, as found in the comments at http://mydrupalblog.lhmdesign.com/classes-almost-everything-drupal-theme