jQuery add target="_blank" for outgoing link

$('a[href^=http]:not([href^=http://www.gusdecool.com/])').attr('target','_blank');

Of course, this works only if all the external links start with the http protocol. You should adapt this code to suite your needs (suchs as links without protocols, or with different protocols).

UPDATE :

$('a[href^=http]:not([href^=http://www.gusdecool.com],[href^=http://gusdecool.com])')
    .add('a[href^=www]:not([href^=www.gusdecool.com])')
        .attr('target','_blank');

It selects all the a elements that have their href attribute starting with a web page address (with or without protocol) and do not point to your site's address and changes their target attribute to _blank.

$('a').each(function() {
   var a = new RegExp('/' + window.location.host + '/');
   if (!a.test(this.href)) {
      $(this).attr("target","_blank");
   }
});

This was from css-tricks.com, seems to work pretty well.

assuming that all external links will start with http:// you could do this:

$('a[href^="http://"]').not('a[href*=gusdecool]').attr('target','_blank');