A lot of good advice here!

As someone who has also managed to fill a passport in less than 12 months, I thought I'd add my own two cents:

1) Always bring a complete change of clothes with you in your carry on bags. There are so many obvious circumstances you'll be glad to have them that I won't bother listing any.

2) I always travel with the Sportswash Company's Facial Fabrics product. (Scroll down that page to find it.) These are like monster wash&drys in a resealable pouch that you can clean your entire body with. They're light weight, great for camping too, and whether you're stuck in the airport overnight or just leaving the plane after a long flight, you'll be happy to have them. (My BOB and home emergency kit have ample supplies of their Sports&Leisure wash. Nothing like being able to take a shower of sorts to give you back a sense of normalcy.)

3) Good earplugs and an eyemask will let you sleep on plane, in an airport, or anywhere else for that matter. (By the way, having tried every eyemask in existence, I think Eagle Creek's is the undisputed champion.)

4) Also, an inflatable neck pillow is the road warrior's secret weapon. It holds your head still so you can fall asleep.

5) Food & water were already mentioned but I'll add 'em anyway. Don't rely on other people to nourish you... I was once stuck in a 3rd world airport when all the workers went on strike. Everything was closed and I have to say my Poptarts never tasted so good.

I guess this is all a little off-topic for this board, but if you travel a lot, a little comfort goes a very long way.