This makes sure external links are opened in new window and applies UTM parametres for statistics.

jQuery - External links

  jQuery(document).ready(function($) {
    $.expr[':'].external = function(obj) {
		  return !obj.href.match(/^mailto\:/) && (obj.hostname != location.hostname);
  	};
  	$('a:external:not(.nonfadelink)').each(function() {
  		$(this).addClass('external').attr("target","_blank");
  		var url = $(this).attr("href");
  		$(this).html(function() {
  			var utms = "<?php echo get_bloginfo('name'); ?>";
  			var utms = utms.split(' ').join('_');
  			var utmc = "<?php echo get_the_title( $post->ID ); ?>";
  			var utmc = utmc.split(' ').join('_');
  			$(this).attr("href", url + "?utm_source=" + utms + "&amp;utm_medium=link&amp;utm_campaign=" + utmc + "").text();
  		});
  	});
  });