DjVu is a web-centric format for distributing documents and images. DjVu was created at AT&T Labs-Research and later sold to LizardTech Inc. DjVuLibre is a GPL implementation of DjVu maintained by the original inventors of DjVu.
Free editor for PDF documents. Complete editing of PDF documents is possible with PDFedit. You can change raw pdf objects (for advanced users) or use many gui functions. Functionality can be easily extended using a scripting language (ECMAScript).
Comix is a user-friendly, customizable image viewer. It is specifically designed to handle comic books, but also serves as a generic viewer. It reads images in ZIP, RAR or tar archives (also gzip or bzip2 compressed) as well as plain image files.
xCHM is a cross-platform GPL frontend for CHMLIB (http://www.jedrea.com/chmlib/) written with the wxWidgets framework.
A tool to organize your pictures
The Java Picture Organizer application lets users build collections of images that they can then search, browse, show and share with others. An HTML export facility is available that allows web pages to be generated.