PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
PDFTools by SheelApps - PDFTools
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
PDFsam - PDFsam Basic, a free, open source, multi-platform software designed to split, merge, extract pages, mix and rotate PDF files
PDFill - Open, View, Edit, Save and Print PDF Documents without Adobe Acrobat
PDF Architect - PDF Architect is a PDF Editor with free functions like rotate, delete and move pages and even more...