Put some high energy bars in your pocket and there are drinking fountains in the halls.
The number one concern is shear boredom... have your phone fully charged and a game or two loaded, bring a notebook and take notes, etc.
A good fun game is to print out the pictures of the Committee members and make notes on the back as each speaks (or just record their actions) and then you can write them a personal email afterwards answering their questions, correcting concepts they did not understand, or just commenting on their attentiveness or lack there-of. Remind them that you were there and that you were watching them.
