can combine, split, rotate, reorder, watermark, encrypt, sign, and otherwise tweak PDF files
jPdf Tweak - Swiss Army Knife for PDF fileshttp://jpdftweak.sourceforge.net/
jPDF Tweak is a Java Swing application that can combine, split, rotate, reorder, watermark, encrypt, sign, and otherwise tweak PDF files.
You can use it to make printable booklets from your PDFs, to add PDF bookmarks, effects (page transitions), to combine multiple PDF files, to watermark them, to rotate pages that do not fit, to attach files to your PDF, to encrypt and sign your PDFs, to change metadata (like author or keywords), and much more.
You might want to have a look at the manual.
jPDF Tweak uses the excellent iText library for manipulating PDF files, and JGoodies Forms for the GUI.
jPDF Tweak requires Java 5 or higher. You can download it from Sun.
There are two binary versions available, a compact one and a normal one. The compact one uses an obfuscator to make the application smaller. So, the compact one has the same features as the normal one. Only if you have problems using the compact one for a task, or if you want to report a bug, try the normal one. The normal version produces better error messages, and - of course - the obfuscator might have bugs as well. If you want to download the libraries separately, there is another version without libraries available (it won't work without libraries).