I figured out how to turn off the annoying hovery thing that says "So-and-so is your mutual friend" and "This is you" and other such useless nonsense:
From any page where you get the normal LJ menu bar (like your user info page), do "Profile" / "Edit Profile"; then where it says "You may also want to edit your comment settings or your viewing options" click the "viewing options" link. Near the bottom there's a check box that says "Contextual Popup" -- turn that off and click the "Save Changes" button at the bottom, and Bob's your uncle.
From any page where you get the normal LJ menu bar (like your user info page), do "Profile" / "Edit Profile"; then where it says "You may also want to edit your comment settings or your viewing options" click the "viewing options" link. Near the bottom there's a check box that says "Contextual Popup" -- turn that off and click the "Save Changes" button at the bottom, and Bob's your uncle.