and I spent ages on it. oh well, try again....
If you have enough room, take comfort foods -notably condiments.(favourite peanut butter, maple syrup etc). Take extra underwear and toiletries -it can be more frustrating than you expect not to be able to find a brand of deodorant you like (in a last straw sort of a way).
I usually forget to pack Beest's hairbrush becasue I don't use one. Of course he could do his own packing, but we usually like to leave in the same millenium.
Beest(I) often forget(s) to pack his belt if he travels in a pair of trousers for which a belt is not required. Which means I can go undisciplined for weeks, even if I did forget the hairbrush.
So check for things you don't use everyday.
Pick up a bottle of Bourbon or similar at Duty Free -great ice-breaker at British Unis.
If you're likely to get homesick at thanksgiving, take something to help you with that.
American Expats can be a good resource for sourcing things you've forgotten.