What do you carry on?
 

I am not well traveled but I must have my sheet/blanket so I can sleep. Flying makes me nervous so I try to sleep the whole way, gotta have my blanket.

My daughter needs her blankie too ;) (but she is 6)

Me I just take a magazine and an IPOD. Laptop if I'm on business but that stays in the overhead.

I have a bag that fits under the seat. In it I put a change of clothes, toothbrush, my laptop, my camera, and my own blanket. (Other little incidentals as well, but those are the main things)

I use a small carryon that could go under my seat if it needed to (Tom Bihn Western Flyer)

It always contains:
At least one change of clothes
Toilettries
Amazon Kindle 2
Dell Mini9 Netbook
Camera
and sometimes I also pack a Travel Pillow if I have a long flight in coach.

Depends. I try to avoid checking my bag, so my rollaboard has my clothes, toiletries, etc. If I'm bringing my camera, it goes in there (hard to keep a DSLR in a briefcase!) My briefcase has my laptop, a book, a newspaper, my iPod, etc.

If I'm on an overnight, I use the pillow that I got on the CO DO IV Mystery Tour flight (the CO BF pillow) which is really comfortable. My boss is rather jealous that I've got a real nice pillow to use on flights while she uses the flimsy regular pillows.

I always take clothes to see me through the first couple of days. I certainly benefited when BA decided I should spend my whole holiday without luggage.I also take my jewellery as that would be one thing that I would be most upset about losing.

I try very hard to never check luggage - so everything

If I have to check:
Ipod
Books or magazines
Water
Snack (if horrors, stuck in coach)
Eyeshade / Ear plugs (if shorter flight with no amenity kit)
Laptop (if work)
Camera or any other expensive items
Jewelry

Ha Ha - Yup I stepped into that one!

I tend to get creative with the whole carry-on and personal item.

I always wear my leather jacket which has some decently sized pockets. This is where I've usually stuffed:

Sunglasses
Nintendo DS
Headphones
Cell phone
All paperwork for flights/travel

Notably, I always have a fuzzy neck pillow, which is usually crooked over a strap of my laptop case.

In my actual carry-on bag I tend to stuff as many outfits as possible and some basic approved toiletries. My camera goes in as well if I bring it. If it is winter my carry-on can get a bit bloated with scarves, gloves, ear muffs - as none of these are needed in FL ever during the winter but become an immediate need once in Chicago.