Travel backpack

This BAGGU backpack looks genius for traveling. It folds up into its own tiny pocket. So, you can use it for picnics, beaches or exploring; and when you buy too many souvenirs, gifts, clothes and snacks on your trip--poof!--you have an extra bag to carry everything home on the plane. (You always need an extra bag, don't you find?) I just ordered a neon one for future trips.

What are your travel essentials? Red lipstick? Wool socks? A flashlight?
P.S. My #1 beauty product on vacation, five shoes for traveling, and 10 trips for traveling with a baby.