iTeXMac is an integrated software which components are:
- a text editor dedicated to D.E. Knuth's TeX typesetting system
- a frontend to a teTeX like distribution, that includes TeX engines and tools
- a PDF viewer
pdf2oo converts pdf to odf. It creates an image for each page, allowing to overlay drawings and text and export it back to pdf. Handy for rewiews of scientific papers. The closest thing to a free pdf editor, "almost" an openoffice pdf import filter.