Please make the 'update your profile' and 'unsubscribe' pages customizable. Especially useful would be the option to make custom subscriber fields appear in subscriber's 'update profile' page-- or when they are about to unsubscribe. This could prevent subscriber leakage for preventable reasons, such as that they are annoyed at being tagged a certain way, or would read emails if only they were sent at a different time. (UPVOTE IF YOU AGREE!)