You may also want to consider OpenOffice as an alternative to these
software products -- you might have better luck finding the internal
formats of OpenOffice files published and more support in the OpenSource
community for software that reads/writes their file formats.
You know that brings up another great question. Does anyone have a suggestion for PHP -> OpenOffice scripts? Sourceforge has a project that looks interesting... "PHP DocWriter"... does anyone have experience with this or other similar projects?