In seriousness now.
Spare washkit- razorblades, shower gel, soap, etc. It's very expensive on camp.
VERY good insoles- Sorbathane are a tried and tested safe bet. Anything other than the issued green card.
Socks- I wear Outlast hiking socks, and the double layered areas have saved me from blisters countless times.
Sense of humour- An absolute must!
Initiative (The ability to think for oneself)- See above.
For everything else, use the search function as God herself knows the amount of items that have been reccomended to take.