Watermarks (background.sty)
\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{background}
\usepackage{lipsum}
\backgroundsetup{contents={CONFIDENTIAL}}
\begin{document}
\lipsum[1-55]
\end{document}
Download sample-background.tex or sample-background.pdf.