Nurse practitioners provide a wide range of health care services to patients, from assisting physicians to providing acute health care aid. In 2007, the average annual salary for nurse practitioners was $86,486. All nurse practitioners are registered nurses who have completed an advanced degree to prepare for their work in the field. Some of their typical work includes interpreting x-rays, diagnosing illnesses, and referring patients to other health care professionals. Nurse practitioners are also able to operate their own practices, allowing for a great deal of flexibility.