LibreOffice - Draw

Draw lets you produce anything from a quick sketch to a complex plan, and gives you the means to communicate with graphics and diagrams.

Free Open Source Mac OS X Windows Linux BSD

PDFTK Builder

PDFTK Builder is a free graphical interface to for PDFTK, making it much easier to use. It is a easy to use tool to collate (merge), split, encrypt, decrypt, stamp and rotate (only 90°, 180° or 270°) pdf documents.

Free Open Source Windows