A PDF-savvy poster known as "saul" has created large-format wall hangings from several classic, public-domain texts. Not only this, but he has provided step-by-step instructions on how users can create their own.
"saul" has offered both The Origin of the Species -- with the "Ascent of Man" as its background -- and science fiction classic Flatland to interested readers as large format PDF files for printing and use as wall hangings. The instructions on how to create similar wall hangings are available from the Flatlands entry.
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.