=Cool links=
*http://pdfedit.petricek.net/ Visual editor + command line tool.pdfeditor
*http://www.mail-archive.com/poppler@lists.freedesktop.org/msg00334.html There is a Ruby binding, Ruby/Poppler, in Ruby-GNOME2 project.
*http://podofo.sourceforge.net/ which is designed as a PDF parsing library.
*http://www.fauskes.net/ pgf and so.