I brought a small, conservative black purse with car keys, breath strips, a comb, stain stick and ID in it and a professional leather folio with my VMCAS application and appropriate supplemental app in it to review in the time before the interview. At OSU I made sure the folio also had pen and paper because they had informative sessions and student panels, and I wanted to take notes. Make sure you have paper if you want to take notes on the school or hospital, but even if you want to, I wouldn't recommend taking notes in the interview--the interviewers are not there to talk to you, you're there to talk to them! If you want, you can sit down right away afterward and write down the questions you can remember, but any folio you bring should go on the floor with your purse and/or coat if appropriate.
In the car, I brought a stain stick (white silk shell ftw), an extra blouse, hair junk, tissues, make-up and various other doodads--but none of that came in with me (except for another stain stick in the purse--yes I had two!).
I would also second whoever said that if you bring someone, to leave EVERYTHING with them. It's just flustering to have to put a bunch of stuff down, pick it up at the end, worry about stepping on it or dropping it, etc.
