The point of the :// thing is more for links and less for typing in an address bar. Some forums only allow so many characters in the signature and (say it is exampleforums.com), if you type in a url (say example.com) with out http, it will go to exampleforums.com/example.com. Thus a problem. If you type <a href=://example.com>Example</a> it saves characters and wont go to the wrong address.
