Since this list continues to grow, I'll add to it. I also like to label my possessions, and I preprint address labels for postcards to be sent out - so that I don't forget anyone. I also pack Dollar Store rain ponchos, pocket-sized first aid kit, antibacterial wipes, purse-sized flashlight, and just incase - a prescription from Dr. for child ear infection (from airplane or swimming).
Very recent photos kept on my person of the kids with physical characteristics detailed on back such as height, weight, missing teeth, etc. (exclude name/address). Jot down what the kids are wearing each morning before leaving room, especially if going to the WDW parks. I think that if we became separated I would be a frantic mess and having those items on hand could be helpful.
And this is not to be packed, but for the containers of the items to be packed. I made laminated tags for luggage, and since last Sept., also for stroller, backpacks, baby bag, video camera bag, camera bag, etc. with a unique colorful picture (Mr. Potato Head) and I keep a business card inside my luggage, etc. just incase it gets lost (again!). There is too much confusion these days going through airport scanners/x-ray. On the last "four" flights that I took, people mistakenly pulled our articles off the belt. The potato head tags helped me to spot our items easily, and retrieve them from over-anxious, unobservant travelers.
Is anyone packing the kitchen sink -- kidding. Lots of good ideas, but I think the more I can leave out of my suitcase the better off I am. It's taking me years to try to work out my over-packing habit.