PDFTK Builder - PDFTK Builder is a free graphical interface to for PDFTK, making it much easier to use.
PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
GSView - Use Ghostscript GSview to open PDF files with owner password restrictions.
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
A-PDF Restrictions Remover - For 9.99 $ A-PDF Restrictions Remover is extremely easy to use.
PDFill - Open, View, Edit, Save and Print PDF Documents without Adobe Acrobat