I would just do a search on peoples' interview experiences from round 1 on this thread, and also last year's applicant thread. The interview is pretty short on campus, about half an hour, and remember to just be yourself - have experiences on hand to talk about leadership, teamwork, challenges, and failures. Know your resume and have a solid answer for Why Booth, Why Now, and Why an MBA.
I recommend being familiar with the curriculum and courses offered, and also extracurriculars you would be interested in if you attend.