Don't forget to ask questions that show you are interested in the patients and the types of resources available to help them. Demonstrate that you care about the patients by asking about them. Ask about common diagnoses, average length of stay, typical challenges of the job, the heart-warming aspects of the job, etc. Show that you are interested in the patients and in doing the type of work required by the job. Too many people only ask questions that emphasize "What's in it for me?" by focusing on pay, work hours, education available, etc.
Another question I particularly like to ask is "If you were to describe someone as 'a good nurse,' what would that mean to you? How would you describe 'a good nurse?'" It gives you a chance to find out if the interviewer's idea of the type of behavior she likes to see in a nurse matches you very well. If it doesn't match, you probably won't get along very well on the job. It's also a bad sign if you ask this of several people you will be working with and their answers don't agree with each other -- indicating that you will be caught in the middle of co-worker's conflicting expectations.