Different universities will have different questions (yes, i know that doesn't really help much.)
UNSW particularly will ask you questions to assess the content of your character; while most universities will test your ethical reasoning as well. Of course the standard questions regarding your drive to do medicine will be asked in any interview as well as your ambitions; and there are also usually questions that ask you about your life experience.
Bear in mind that while some interviews are structured and ask the same questions to every student, some are semi structured and will ask additional non-scripted questions to further their assessment.
Try here for scenario questions:
http://www.medstudentsonline.com.au/forums/showthread.php?t=4714
