How to pull pictures and summary information from external web pages when posting links?
AFAIK there is no module available for this specific use case. However FBSMP module has its own implementation of crawling links/image/video and other media types from the given URL.

You may need to take that as a base and develop your own version.

Below is the sample code on how its crwaling the links

$result = drupal_http_request($url, array('timeout' =&gt; $options['timeout']));

  if ($result-&gt;code != 200) {
    fbsmp_log_error(t("Could not connect to @url, HTTP error @error", array('@error' =&gt; $result-&gt;code, '@url' =&gt; $url)));
    return $data;
  }

  $page_url = $url;
  if (in_array($result-&gt;redirect_code, array(301, 302, 307))) {
    $page_url = $result-&gt;redirect_url;
    $data['title'] = $page_url;
  }

  if (stripos($result-&gt;headers['Content-Type'], 'image') !== FALSE) {
    $images = array();
    if (($imagesize = _fbsmp_link_validate_filesize($page_url, $options['max_imagesize'], $options['min_imagesize'], ($options['timeout'] - timer_read(__FUNCTION__) / 1000))) != -1) {
      $images[$page_url] = $imagesize;
    }

    $data['images'] = $images;
  }
  else {
    _fbsmp_link_detect_charset($result-&gt;data);

    $document = new DOMDocument();
    if (@$document-&gt;loadHTML($result-&gt;data) === FALSE) {
      fbsmp_log_error(t("Could not parse the content on @url", array('@url' =&gt; $url)));
      return $data;
    }

    $xpath         = new DOMXPath($document);

    //Get title of the page.
    $titles        = @$xpath-&gt;evaluate("//title");
    $data['title'] = trim($titles-&gt;length &gt; 0 ? $titles-&gt;item(0)-&gt;nodeValue : $data['title']);
    //Get description of the page.
    $descriptions  = @$xpath-&gt;evaluate("//meta[@name='description']");
    $data['description'] = trim($descriptions-&gt;length &gt; 0 ? $descriptions-&gt;item(0)-&gt;getAttribute('content') : $data['description']);

    if (!$emfield['emvideo_valid'] &amp;&amp; !$emfield['emaudio_valid']) {
      $hrefs         = @$xpath-&gt;evaluate("/html/body//img");
      $images = array();

      if (!fbsmp_include_library('url_to_absolute.inc', 'url_to_absolute')) {
        fbsmp_log_error(t("Could not find url_to_absolute.inc file in the libraries folder"));
        return $data;
      }

      for ($i = 0; $i &lt; $hrefs-&gt;length; $i++) {
        $image_url = $hrefs-&gt;item($i)-&gt;getAttribute('src');
        if (!isset($image_url) || empty($image_url)) {
          continue;
        }
        $abs_url = url_to_absolute($page_url, $image_url);
        if ($abs_url &amp;&amp; ($imagesize = _fbsmp_link_validate_filesize($abs_url, $options['max_imagesize'], $options['min_imagesize'], ($options['timeout'] - timer_read(__FUNCTION__) / 1000))) != -1) {
          $images[$abs_url] = $imagesize;
        }
        if (($options['timeout'] - timer_read(__FUNCTION__) / 1000) &lt;= 0) {
          fbsmp_log_error(t("Request timed out for @url", array('@url' =&gt; $url)));
          break;
        }
      }
      asort($images);
      $images = array_reverse($images, TRUE);
      $data['images'] = $images;
    }
  }

  //Cache the results.
  if ($options['cached']) {
    cache_set($arghash, $data, 'cache', REQUEST_TIME + $options['cache_duration']);
  }


You may also check following references,


embed.ly
Using Yahoo API to crawl the link