// ==UserScript==
// @name          Find Images with XPath
// @namespace     http://www.dopiaza.org/flickr/greasemonkey/
// @description   Find all images in a page
// @include       http://www.flickr.com/*
// @include       http://flickr.com/*
// ==/UserScript==

var imgElements = document.evaluate(
  "//img[@width='75']",
  document,
  null,
  XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
  null);

for (var i = 0; i < imgElements.snapshotLength; i++) 
{
  var img = imgElements.snapshotItem(i);
  
  var src = img.getAttribute('src');

  GM_log("Found Image: " + src);    
}