Contact form on maintenance mode page
If you are comfortable with Custom coding, you can try following route

On your theme template.php implement template_preprocess_maintenace(), this will help you introducing new variables to maintenance page tpl file, something like below

function yourtheme_name_preprocess_maintenance_page(&amp;$vars) {
  if (function_exists('_your_form_builder_funtion')) {
    $vars['your_custom_form'] = drupal_render(drupal_get_form('_your_form_builder_function'));
  }
}


Now copy the maintenance-page.tpl.php in your custom theme templates folder and on the template file, you can use the variable like any other being already used. So somewhere on your maintenance-page.tpl.php add following

  &lt;div class="contact-form"&gt;
    &lt;?php print $your_custom_form; ?&gt;
  &lt;/div&gt;