jQuery.fn.centerx = function () {
			    this.css("position","absolute");
			    this.css("left", ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + "px");
			    return this;
			}
			
			jQuery.fn.center = function () {
			    this.css("position","absolute");
			    this.css("top", ( $(window).height() - this.height() ) / 2+$(window).scrollTop() + "px");
			    this.css("left", ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + "px");
			    return this;
			}
			
			$(function(){
				$("#header").centerx();
				$("#dropzone, #browser").center();
			});
			$(window).resize(function(){
				$("#header").centerx();
				$("#dropzone, #browser").center();
			});

http://general-metrics.com/

I like how this site uses jQuery to center some elements and I wanted to save the code incase they change their site ever.

Simple element centering with jQuery

jquery

JavaScript