Thanks for the responses. My school ended up posting a huge listing of good callback questions, so that was really helpful. One thing that I've heard on here that I should point out is potentially wrong though. At one of my callbacks (1 of 2) I had multiple interviewers encourage me to ask the same questions of each interviewer. I saw someone saying that this was the best way to get dinged. This may be true of some firms, but clearly not all.