Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
POKATreader - With POKATreader you can read your PDF files in full-screen mode, but one of the best features is...
calibre - Ebook manager, viewer & converter
PDF-XChange Editor - The smallest, fastest, most feature-rich PDF editor/viewer available
Okular - Okular is a universal document viewer based developed by KDE.
PDFZen - The powerful, simple, free online PDF editor for the masses; free yourself from the fax machine!