PDF-XChange Editor - The smallest, fastest, most feature-rich PDF editor/viewer available
PDFzorro - PDFzorro is a web based source for enjoying the professional level of PDF editing.
ScanTailor - Scan Tailor is an interactive post-processing tool for scanned pages.
Nitro Pro - An affordable Adobe Acrobat alternative for editing and creating PDF
Briss - Cross-platform application for cropping PDF files in a simple and fast way via a GUI.
PDFForge - PDFForge is the provider of two PDF management tools in shape of PDF Creator and PDF Architect.