PDF-XChange Editor - The smallest, fastest, most feature-rich PDF editor/viewer available
ScanTailor - Scan Tailor is an interactive post-processing tool for scanned pages.
YASW (Yet Another Scan Wizard) - Download YASW for free.
Briss - Cross-platform application for cropping PDF files in a simple and fast way via a GUI.
PDF Scissors - Crop pdf. Drop margin, whitespace. Auto crop all pages. Easy feature to make nice cropped pdf for ebook readers such as Amazon Kindle, Sony, Cybook etc.
ScanKromsator - Scan Software with several advanced options