How do I show the site-wide contact form on a page in Drupal 7?
You could create a custom block in a module and embed the form there. Something like this (I haven't tested this code!):

/**
 * Implements hook_block_info().
 *
 * This hook declares what blocks are provided by the module.
 */
function MODULENAME_block_info() {

  $blocks['contact_block_form'] = array(
    'info' =&gt; t('Contact Form'),
    );

  return $blocks;
}

/**
 * Implements hook_block_view().
 *
 * This hook generates the contents of the blocks themselves.
 */
function MODULENAME_block_view($delta = '') {
  //The $delta parameter tells us which block is being requested.
  switch ($delta) {
        case 'contact_block_form':
      $block['subject'] = t('Contact Us');
      // Load contact pages inc as the form definition sits there.
          module_load_include('inc', 'contact', 'contact.pages');
      $block['content'] = drupal_get_form('contact_site_form');
    break;
  }
  return $block;
}


Hope this helps