Calculator & Clicker (Small and lightweight, and both can be extremely useful)
Airplane pillow & Space blanket
Pen and journal for assistance in the inevitable memory task.
CLOTHING!!! All rolled, and cheap shirts that I don't care about so I can jettison them when I'm done with them. Maybe 1 or 2 outfits that I really care about and will wear for the finals.
A bag full of deoderant, toothpaste, etc
And if it would fit, and it exists, a book of simple phrases in many languages (Spanish, Portugese, Chinese, French. As many languages as possible.)