Don't make the link clickable. You want the focus to be drawn towards the slogan/question you have underneath and you want the user to sign up or login. You cou

Don't make the link clickable. You want the focus to be drawn towards the slogan/question you have underneath and you want the user to sign up or login. You could also display a few more sites-in-common underneath the sign up and login buttons just to show that the thing actually works.