Off the top of my head:
a) Pens of your preferred writing colour. I'd suggest black, as this is the colour you need to write your exams in.
b) Other coloured pens, eg. green, red, etc.
c) Sticky notes, both the ordinary square shaped ones to put notes down on and the small, rectangular ones to keep pages you find important in textbooks / etc.
d) Highlighters!
e) Your preferred type of pencil.
f) A geometry set.
g) A scientific calculator.
h) A notebook. I really like the ones with dividers to seperate the notes from your different subjects!
i) Plastic wallets.
j) File.
k) File dividers to seperate your different subjects.
l) Labels. During my exams, I took notes on a topic within a subject (eg. histograms in Maths) and I'd put all that work in one plastic wallet and label it, "Histograms." I found it to be really helpful.
m) Rubber / eraser and sharpener, if they have not already been provided by the above listed items / deemed unecessary.
Sorry if I've missed any out. Good luck with your exams!