A flat bed

My Technics headphones
A fully charged iPod
My laptop with lost of movies (just in case the IFE is once again broken)
The charger of my laptop in the hope there are power outlets in the seats.
Some snacks
Tons of water (yes, it really does help to fight a jetlag)
A pen (however, I always tend to lose it onboard, I really do every time)
Some basic medicines (head, stomach, throat,)
And the most important of course: my passport.

iDevices: MacAir, iPad, & iPhone
Etymotic in-ear headphones

In my carry-on bag I'll usually have a passport, pen, camera, book, eye shade, eye drops, lip balm, deodorant, adapters/chargers, and a hoodie/sweatshirt. Of those, I'll bring the passport, pen, book, hoodie, and eye shade to my seat before stashing the bag in the overhead bin.

My iPod and my MacBook Pro, as long as I have those two things I'm usually happy. Well, at least once they start serving drinks! :p

0) An F or a J Boarding Pass

Nowadays.. earphones.. to pass the time with airline entertainment..

cc, to buy food when we need it..

Wallet
Cell Phone
Tablet
Eye drops
xanax
ear phones

Kindle loaded with books that I can't wait to read
Ipad
Travel chess if I'm travelling with Mr.Geek007
Eye shade
Basic meds
Drawing pens and a sketch book
Travel guide to wherever I'm headed
Snacks such protein bars
Water bottle
Laptop if I'm travelling for work
Noise cancelling headphones
and if it's an over night flight I will not fly sans Ambian

Ear plugs, eye shades, fleece jacket, enough to read.

What would you not be without on a long flight?
 

A business class seat.

And my cpap machine with mask, etc.

Passport
Kindle
Large bottle of water
(Pens etc in my handbag - and no flight is so long that I can't make do with the toiletries in the amenity kit!)

noise canceling headphones!
earplugs
pashmina
magazine
Kindle

o and a systemwide upgrade! :D