Before I began my interview process, my first student host sent me his "Checklist". I copied it below:
Suit
Jacket , Pants, Belt
Shoes, 2 pair dress socks
2 pair underwear & shirt garters
Crew neck undershirt
Dress shirt & tie
Tide pen located in jacket (all packed in travel bag)
Portable travel steamer
_________________________________________________________________________
Recreational
White socks/travel socks
Sleep shirt and shorts
Workout clothes (if necessary)
_________________________________________________________________________
Interview Related
Leather portfolio w/ paper, business cards, photos, etc.
Tickets and flight confirmation
Hotel or lodging confirmation
AMCAS Primary and School-specific Secondary Applications
iPhone, BlackBerry, and associated charging devices
_________________________________________________________________________
Miscellaneous
GPS w/ Charger
Dopp kit (toothbrush, fresh razor, medicine, shaving cream, deodorant, liquids)
Book (medicine or school)
Address and specific time of interview
Headphones and sleep kit
Credit card and $100+ in cash
Hand towel
Apart from those things mentioned, I also brought a camera. Once my interview concluded I took pictures of the medical campus, any signs or other noticeable landmarks that may help me remember specifics about the day. It sounds unnecessary, but after you interview at 6 or 7 campuses, they all seem to blend together.
In addition, I printed off my secondary for that particular school (including essays) as well as potential interview questions from that school. I kept both in my portfolio and reviewed approximately 10 minutes before my interview.