jQuery: Navigation that sticks to the top once the specified threshold has been passed.

jquery-fixed-navigation.js

var fixed = false;

jQuery(document).ready(function($) {
	$(window).scroll(function() {
		if ($(this).scrollTop() >= 100) {
			if (!fixed) {
				fixed = true;
				$('#navigation').css({
					position: 'fixed',
					top: 0
				});
			}
		} else {
			if (fixed) {
				fixed = false;
				$('#navigation').css({
					position: 'absolute',
					top: 90
				});
			}
		}
	});
});