Don't forget your photo ID. Refer to the NCEES instructions as well. I also took snacks, water, tums, psuedfed, ibproufen, ear plugs, gum. Of course I didn't use most of the medication, but I did get heartburn after eating burritos for lunch, so the Tums came in handy. I had a lunch in the car, waiting for me, but ran into a couple old friends that were also taking the exam so we went and grabbed lunch.
Make sure you're back on time after lunch though. The girl who was sitting behind me didn't come back. About halfway through the instructions I could see her just outside the glass door clearly arguing with the proctor assigned to guard the door. Would hate to be in her shoes.
You can leave your reference material and calculator. They will check your calculator and stuff again in the afternoon.