ScanTailor - Scan Tailor is an interactive post-processing tool for scanned pages.
PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
Briss - Cross-platform application for cropping PDF files in a simple and fast way via a GUI.
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
ScanKromsator - Scan Software with several advanced options
PDFill - Open, View, Edit, Save and Print PDF Documents without Adobe Acrobat