Parallaxin'. Derived from http://net.tutsplus.com/tutorials/html-css-techniques/simple-parallax-scrolling-technique/

01-html_markup.html

<section data-type="background" data-speed="10">
</section>

02-css.css

section {
	background: url(path/to/background) 0 0 repeat fixed;
}

03-jquery.js

$(document).ready(function() {

	//  $$$$$$$\                              $$\ $$\                     $$\         $$\
	//  $$  __$$\                             $$ |$$ |                    \__|        $  |
	//  $$ |  $$ |$$$$$$\   $$$$$$\  $$$$$$\  $$ |$$ | $$$$$$\  $$\   $$\ $$\ $$$$$$$\\_/
	//  $$$$$$$  |\____$$\ $$  __$$\ \____$$\ $$ |$$ | \____$$\ \$$\ $$  |$$ |$$  __$$\
	//  $$  ____/ $$$$$$$ |$$ |  \__|$$$$$$$ |$$ |$$ | $$$$$$$ | \$$$$  / $$ |$$ |  $$ |
	//  $$ |     $$  __$$ |$$ |     $$  __$$ |$$ |$$ |$$  __$$ | $$  $$<  $$ |$$ |  $$ |
	//  $$ |     \$$$$$$$ |$$ |     \$$$$$$$ |$$ |$$ |\$$$$$$$ |$$  /\$$\ $$ |$$ |  $$ |
	//  \__|      \_______|\__|      \_______|\__|\__| \_______|\__/  \__|\__|\__|  \__|
	//
	//
	//
	var $window = $(window);

	$('section[data-type="background"]').each(function(){
		var $bgobj = $(this); // assigning the object

		$(window).scroll(function() {
			var yPos = -($window.scrollTop() / $bgobj.data('speed'));

			// Put together our final background position
			var coords = '50% '+ yPos + 'px';

			// Move the background
			$bgobj.css({ backgroundPosition: coords });
		});
	});

});