If you are reading text in at least Safari 4 or later which contains a web address in plain text (it isn’t actually linked), you can highlight the URL, then right-click to reveal 3 custom sub-menus: “Go To Address”, “Go To Address in new Window” and “Go To Address in New Tab.” You can try it on the URLs on this page, because we can’t try it here—Tumblr auto-links plain text URLs.
Editor’s Note: Can anyone verify if this works in Safari 4 or 5 on 10.5 Leopard? I’m not sure if this is solely a Safari feature or if it’s dependent on text features in 10.6 Snow Leopard.