Medical- first aid kit, identification
Shelter- rain gear
Fire- lighter, matches
Hydration- bottle of water, straw, water treatment method
Communication- cell phone, whistle, pencil/paper
Navigation- compass, gps (smart phone), headlamp
Nutrition- extra food
Insulation- jacket, hat, leather gloves
Sun Protection- use clothing to cover up
Tools- swiss army knife, p38, money, walking shoes
I like to think of these things in terms of categories, before the specific gear. This is a great breakdown of categories of equipment to consider. For the stuck in an airport/train station/hotel scenario, I'd add the categories of
Light and
Hygiene, probably at a higher priority than fire.
Comfort might also be a category to consider. (i.e. pillow, ear plugs, etc.)
On the subject of Navigation, having contact info and maps for the local area you'll be traveling to is a good idea. Which reminds me - cash is king. Shelter, food, navigation, water, communications.... they can all be enhanced by cash most of time.
I also always try to have an extra change of climate appropriate clothes.