gallery.js

function($){  
  $.fn.gallery = function(settings) {

    var config = {
        activeelm: 'active',
        nav: 'nav',
        navnext: 'nxt'
    }; 

    if (settings) $.extend(config, settings);
    
    var $gallery = $(this);

    // Hide the image elems
    $gallery.children().addClass("hide");
    
    // Preload Images
    preloadImages();

    // Setup Click Handler
     $("." + config.nav).children("a").click(function(){
       $(this).hasClass(config.navnext) ? changeimage("next") : changeimage("prev");   
       return false;
     });

     // Setup Keyboard Handler
     $(document).bind('keydown',function(event){ 
       if (event.keyCode == '37') {
         changeimage("prev");             
        } else if (event.keyCode == '39') {
         changeimage("next");       
        }
     });

     // Finally call changeImage with empty arguments to do initial setting up
     changeImage();

     function changeimage(action) {
       var currentelm = $gallery.children("." + config.activeelm);      
       if(action === 'next') {
         var nextelm = $(currentelm).is(':last-child') ?  $(currentelm).siblings(':first-child') : $(currentelm).next();        
       } else if(action === 'prev') {
         var nextelm = $(currentelm).is(':first-child') ?  $(currentelm).siblings(':last-child') : $(currentelm).prev();        
       }
       // TODO handle case of empty args       
       // Move history updating to a separate function, like updateLocationBar, and you will also need 
       // another function called readLocationBar
       window.location = window.location.href.replace(/\#.*/,'') + '#' + $(nextelm).children("img").attr("src");

       $(currentelm).removeClass(config.activeelm).addClass("hide");
       $(nextelm).removeClass("hide").addClass(config.activeelm);       
     };

     function preloadImages(){
       // TODO show some sort of loader graphic
       $gallery.find("img").each(function(){  

         var imagesrc = $(this).attr("src");
         if ($.browser.msie) {
          new Image().src = imagesrc;
          return;
         };
         o = document.createElement('object');
         o.data = imagesrc;
         o.width = o.height = 0;
         document.body.appendChild(o);           
       });
     };
  }
}(jQuery);