As on twitter.com:
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-XXXXX-X']);
_gaq.push(
['_trackPageview'],
['_setDomainName', 'twitter.com']
);
(function() {
var ga = document.createElement('script');
ga.type = 'text/javascript';
ga.async = true;
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script')[0];
s.parentNode.insertBefore(ga, s);
}());
</script>
Which can be reduced to:
<script>
var _gaq=[['_setAccount','UA-XXXX-X'],['_trackPageview'],['_setDomainName','twitter.com']];
(function(d,t){
var g=d.createElement(t),s=d.getElementsByTagName(t)[0];
g.async=1;
g.src='//www.google-analytics.com/ga.js';
s.parentNode.insertBefore(g,s)
}(document,'script'));
</script>
And with $script.js:
<script>
$script("//www.google-analytics.com/ga.js", function(){
var t = _gat._getTracker ("UA-XXXXX-X");
t._setDomainName("twitter.com");
//t._initData();
t._trackPageview();
});
</script>