Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.
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.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
Briss - Cross-platform application for cropping PDF files in a simple and fast way via a GUI.
Wondershare PDFelement - All-in-one PDF editor
PDF-XChange Editor - The smallest, fastest, most feature-rich PDF editor/viewer available