In my carry on for a 30+ hour trip from Boston to Australia-

A quart sized bag with eye drops, lotion, Motion-eaze (have found that even if I don't have motion sickness, the smell of this stuff is relaxing), biofreeze (great for sore muscles), toothpaste, deodorant.
Toothbrush
A change of clothes
My camera
A comb or brush
Wet wipes to freshen up
iTouch and headphones
Phone and charger though I can't use it where I am going
A few snacks
My travel wallet (which can also hang around my neck as needed) that has money of both currencies, my passport, boarding passes, important information such as numbers, pictures of my luggage as it looked upon leaving, a pen, etc.
My sleep meds
Sometimes an allergy med in case they flare up

In addition to my carry on, I also bring my laptop in a backpack, a fleece tied around my waist, and a memory foam neck pillow (so much better than the regular ones). I have enough stuff to do on my itouch and IFE that I stay pretty comfortable for the whole flight.