I have been looking for an open source editor that is comparable to Acrobat Pro for years. In fact, this and that it is not even acknowledged that such an essential tool for office workers is missing in Linux are among the main reasons I don't ditch Windows on my main machine.

PDF Arranger, Ghostscript and Master PDF are indeed useful.

PDF4QT was not mentioned by others. It works well already and is a very promising PDF viewer, organiser, editor. I am not sure why it has to be split into three applications.