function setupExternalLinks() {
    $('a').each(function() {

        var anchor = $(this);
        var rel = anchor.attr('rel');
        var url = anchor.attr('href');

        if (rel == 'external')
            anchor.attr('target', '_blank');

        if (rel == 'top')
            anchor.attr('target', '_top');
    });
}

window.onload = setupExternalLinks;