PDFTK Builder - PDFTK Builder is a free graphical interface to for PDFTK, making it much easier to use.
PDFtk - PDFtk is a simple tool for doing everyday things with PDF documents.
PDF Arranger - Small python-gtk application, which helps the user to merge or split pdf documents and rotate, crop...
Pdfinfo - Pdfinfo is a PDF document information and metadata extractor tool.
Debenu PDF Tools - Simple to use solution to merge PDF files, edit document properties, add and edit custom metadata, convert images to PDF, convert PDF to text and much more.
Edit PDF metadata - Edit PDF metadata is an online tool from PDFCandy that can manipulate PDF info and metadata.