I'm positively thrilled with the release of Snakes on a Plane just last week (don't judge me for it!). Whilst I haven't had a chance to see it just yet (this Thursday), I did have a chance to look over a few PDFs on a plane during an overseas trip to China last week.
Specifically, the one I found most interesting was called "How to Avoid Deep Vein Thrombosis on Long Plane Flights":
"Concern about deep vein thrombosis (DVT), a potentially life-threatening disorder in which blood clots form in the deep veins of the body, particularly the legs, has been growing in recent years after several cases were attributed to long flights."
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.