PDFtk - PDFtk is a simple tool for doing everyday things with PDF documents.
DocuPUB - DocuPUB is an online file converter, file merger, file compressor, and file resizing tool.
AutoMetadata - AutoMetadata is a tool for exploring and manipulating metadata, document properties, and viewer preferences in multiple PDF documents.
PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
Edit PDF metadata - Edit PDF metadata is an online tool from PDFCandy that can manipulate PDF info and metadata.
7-PDF Split & Merge - Functions: Split pdf-files, Merge pdf-files together