Adobe Acrobat Reader allows you to view, comment, fill out, and sign PDFs on multiple platforms.
Free and open-source graphical interface for pdftk (PDF Toolkit), a command-line tool used to manipulate PDF files.
Free software that allows you to merge multiple pages of PDF documents into a single page.
Software for reading and printing PDF documents.
Small utility that allows you to easily split pages of PDF files.
Free software for Windows that allows scanning and saving documents in PDF format.