Wowsers! This is page is old, head to the LIVE Planet PDF Forum. It features more than 10 conferences, covering everything from beginner to in-depth developer and pre-press discussions. If you wish to continue... one & two archive covers 1999-2011 (160,000 pages).
Planet PDF talks with another Master of the PDF Universe, Eugene Y. Xiong, Founder and Chairman of the Board at Foxit Software Inc. in Fremont California. Xiong is a quiet yet astounding achiever, you (usually) won't find him talking at conferences, exhibits, or publishings, but what you will find is the result of his leadership in places you would never expect.
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.