Instead of using each time attribute target="_blank" for hyperlinks you can use jQuery.

$().ready(function () {
    $('a[href^=http]').addClass('external').attr('target', '_blank');

On loaded page jQuery selects all links on the page which begins with 'http', applies class "external" and adds attribute "target=_blank". Example any external link on this webpage. Is it not simple and nice? BTW, Strict HTML don’t allow using target=_blank attribute.