function keys(key) {
  if (!key) key=1;
  if (key.target) key=key.which;
  if (key.keyCode) key=key.keyCode;
  var links = document.getElementsByTagName('link');

  if (key == 37 || key == 33 || key == 38 || key == 74) {
    /* go backwards */
    for (var i=0; i<links.length; i++) {
      if (links[i].getAttribute("rel") == "prev") {
       document.location = links[i].getAttribute("href");
      }
    }
  } else if (key == 39 || key == 1 || key == 32 || key == 34 || key == 40) {
    /* advance */
    for (var i=0; i<links.length; i++) {
      if (links[i].getAttribute("rel") == "next") {
       document.location = links[i].getAttribute("href");
      }
    }
  }  
}

document.onkeyup = keys;
document.onclick = keys;