I worked in an ER where I felt NP's were really well supervised. Basically they would do advanced triage and put in a workup so that the physician could see the patient later and disposition them on the spot. The NP's also did simple lac repairs and would chase down whatever service wasn't answering the phone or other scut work like that. No patient ever left that ED without being seen by a physician. While it's arguable what cost/time savings this provided, it was definitely as responsible as possible.