simple retrieve web page and parse dom using xpath via http://sites.google.com/site/webdevedu/lessons-1/php-basics#TOC-Accessing-web-services

access-parsedom-web-services.php

<?php
$url = "http://icanhascheezburger.com";
  $html = file_get_contents($url);
  $dom = new DomDocument();
  @$dom->loadHTML($html);
  $xpath = new DOMXPath($dom);
  $img = $xpath->evaluate("//div[@class='entry']//img")->item(0);
  $imgSrc = $img->getAttribute('src');
  print("<img src=\"$imgSrc\" />");