function externalLinks()
{
	if ( !document.getElementsByTagName )
		return;
		
	var anchors = document.getElementsByTagName('a');
	
	for ( var i = 0; i < anchors.length; i++ )
	{
		var anchor = anchors[i];
		if ( anchor.getAttribute('href') && anchor.getAttribute('rel') == 'external' )
			anchor.target = '_blank';
	}
}

window.onload = externalLinks;