@markylit points out, nurse anesthetist is a highly paid speciality but it you want to make even more money you would need a doctorate in nursing.
According to this site salaries can be very, very good for nurses with advanced degrees. Administrative positions, like head of nursing pay well to as you can see.
Chief Nurse Anesthetist: $172,724
Head of Nursing: $177,500
This site discusses the varies types of doctoral and Ph.D programs available in the field of nursing and what types of careers those programs would prepare you for. Nursing is a pretty wide open field with the right education, training and experience.