From the WIKI:
How can I show the amount of stock available next to each attribute on the product information page?
This wiki page points to posts that are not publicly viewable. I have one attribute in a dropdown for a product and here is how I did it, hopefully this saves someone a little bit of time.

zen cart version = 1.3.8a

in includes\modules\attributes.php

after
Code:
die('Illegal Access');
}
add the following:

Code:
//START PWA EDIT
  function zen_draw_pull_down_menu_disableable($name, $values, $default = '', $parameters = '', $required = false) {
    $field = '<select name="' . zen_output_string($name) . '"';
    if (zen_not_null($parameters)) $field .= ' ' . $parameters;
    $field .= '>' . "\n";
    if (empty($default) && isset($GLOBALS[$name])) $default = stripslashes($GLOBALS[$name]);
    for ($i=0, $n=sizeof($values); $i<$n; $i++) {
      $field .= '  <option value="' . zen_output_string($values[$i]['id']) . '"';
      if ($default == $values[$i]['id']) {
        $field .= ' selected="selected"';
      }
      if ($values[$i]['disabled'] == true) $field .= ' disabled="disabled"';
      $field .= '>' . zen_output_string($values[$i]['text'], array('"' => '&quot;', '\'' => ''', '<' => '&lt;', '>' => '&gt;')) . '</option>' . "\n";
    }
    $field .= '</select>' . "\n";
    if ($required == true) $field .= TEXT_FIELD_REQUIRED;
    return $field;
  }
//END PWA EDIT

after
Code:
if ($pr_attr->fields['total'] > 0) {
add the following:

Code:
//START PWA EDIT
$PWALookup = array();  
$PWAQ = $db->Execute("
select 
  products_with_attributes_stock.quantity as q, 
  products_attributes.options_values_id as id
  from products_with_attributes_stock
  left join products_attributes on products_with_attributes_stock.stock_attributes = products_attributes.products_attributes_id
  where products_with_attributes_stock.products_id='".(int)$_GET['products_id']."'
");
if ($PWAQ->RecordCount() > 0) {
do {
  $PWALookup[$PWAQ->fields['id']] = $PWAQ->fields['q'];
  $PWAQ->MoveNext();
} while (!$PWAQ->EOF);
}
//END PWA EDIT
find the following:

Code:
$products_options_array[] = array('id' => $products_options->fields['products_options_values_id'],
                  'text' => $products_options->fields['products_options_values_name']);
replace with:

Code:
//START PWA EDIT
$PWAkey = $products_options->fields['products_options_values_id'];
$PWAAppend = "";
$PWADisabled = false;
if (array_key_exists($PWAkey ,$PWALookup)) {
    if ($PWALookup[$PWAkey] == 0) {
        //out of stock message
        $PWAAppend = " (Out of stock)";
        $PWADisabled = true;
    } else {
        //your IN STOCK message goes here
        $PWAAppend = " (".$PWALookup[$PWAkey]." in stock)";
    }
}
$products_options_array[] = array('id' => $products_options->fields['products_options_values_id'].$PWAHack,
'text' => $products_options->fields['products_options_values_name'].$PWAAppend,'disabled'=>$PWADisabled);
//END PWA EDIT
find the following code

Code:
$options_menu[] = zen_draw_pull_down_menu('id[' . $products_options_names->fields['products_options_id'] . ']', $products_options_array, $selected_attribute, 'id="' . 'attrib-' . $products_options_names->fields['products_options_id'] . '"') . "\n";
replace with:

Code:
//START PWA EDIT
$options_menu[] = zen_draw_pull_down_menu_disableable('id[' . $products_options_names->fields['products_options_id'] . ']', $products_options_array, $selected_attribute, 'id="' . 'attrib-' . $products_options_names->fields['products_options_id'] . '"') . "\n";
//END PWA EDIT