The parallax effects with jQuery

/* CSS */
.section {        width:540px; height:500px;
background:url(images/bg_freext.jpg) no-repeat #000; }
.section .inner { width:540px; height:500px;
background:url(images/fg_freext.png) no-repeat; }



/* jquery code */
// The plugin code
(function($){
$.fn.parallax = function(options){
var $$ = $(this);
offset = $$.offset();
var defaults = {
"start": 0,
"stop": offset.top + $$.height(),
"coeff": 0.95
};
var opts = $.extend(defaults, options);
return this.each(function(){
$(window).bind('scroll', function() {
windowTop = $(window).scrollTop();
if((windowTop >= opts.start) && (windowTop <= opts.stop)) {
                    newCoord = windowTop * opts.coeff;
                    $$.css({
                        "background-position": "0 "+ newCoord + "px"
                    });
                }
            });
        });
    };
})(jQuery);

// call the plugin
$('.section').parallax({ "coeff":-0.65 });
$('.section .inner').parallax({ "coeff":1.15 });

http://www.franckmaurin.com/the-parallax-effects-with-jquery/ http://stephenmcintyre.net/blog/jquery-parallax-scrolling/