PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
PDF-XChange Editor - The smallest, fastest, most feature-rich PDF editor/viewer available
DocuPUB - DocuPUB is an online file converter, file merger, file compressor, and file resizing tool.
ScanTailor - Scan Tailor is an interactive post-processing tool for scanned pages.
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
Briss - Cross-platform application for cropping PDF files in a simple and fast way via a GUI.