var selected = null, slides = null, current = 0;

window.onload = function() {
  slides = $get("#billboard img");
  if (slides != null) {
    for (var i = 0; i < slides.length; i++) { slides[i].setOpacity(0); slides[i].hide(); };
    slides[current].setOpacity(100);
    slides[current].show("inline");
    
    window.setInterval(function() {
      var curr = slides[current];
      var next = slides[(current < slides.length - 1 ? ++current : current = 0)];
      curr.fadeOut({increment: 1, speed: 10, callback: function() {
        curr.hide();
      }});
      next.show("inline");
      next.fadeIn({increment: 1, speed: 10});
    }, 5000);
  };
};