PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
PDFTK Builder - PDFTK Builder is a free graphical interface to for PDFTK, making it much easier to use.
DocuPUB - DocuPUB is an online file converter, file merger, file compressor, and file resizing tool.
PDF Arranger - Small python-gtk application, which helps the user to merge or split pdf documents and rotate, crop...
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
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.