Very nicely used Google Analytics tracking code.

ga_tracking.js

    $("a").click(function() {
    	var href, href_lower;
    	href = ($(this).attr("href") === undefined ? "" : $(this).attr("href"));
    	href_lower = href.toLowerCase();

    	if (href_lower.substr(-3) === "pdf" || href_lower.substr(-3) === "xls" || href_lower.substr(-3) === "doc") {
    		_gaq.push(["_trackEvent", "document", "download", href_lower.substr(-3), $(this).text()]);
    		_gaq.push(["_trackPageview", href]);
    	}
    	if (href_lower.substr(0, 4).toLowerCase() === "http") {
    		_gaq.push(["_trackEvent", "external_link", "open", "href", $(this).text()]);
    		_gaq.push(["_trackPageview", href]);
    	}
    	if ($(this).attr("target") !== undefined && $(this).attr("target").toLowerCase() !== "_blank" && href_lower.substr(0, 10) !== "javascript") {
    		setTimeout((function() {
    			location.href = href;
    		}), 200);
    		return false;
    	}
    });