I fully applaud your work on promoting the fact that there exist Open versions of PDF, as produced by the ISO. It would be nice, however, if you provided links and/or names for these - ISO 32000 (PDF), ISO 19005 (PDF/A), ISO 24517 (PDF/E) and ISO 15930 (PDF/X).
In addition, I welcome your promoting the existence of the various free PDF readers that are available to users on various OS platforms.
However, I noticed that you've chosen to leave visibly absent the lack of overlap between these two things. It is EXTREMELY important for users to know that while these free readers exist - NONE of them support ANY of the Open versions of PDF.
While the FSF is working on their GnuPDF project, to provide an ISO 32000 compliant viewer - it will be a while before that materializes. In that time, I would think that users of free products would want/expect their products to comply with open standards. As such, I think that an excellent use for yourselves and your site would be to work with to promote that effort.
I, myself, am quite active in that effort and in free/open PDF efforts. I have been an active participant on every major free/open PDF-related project for over 10 years now! I will continue to help work with these projects to help them achieve this goal - and would love all the help you can offer...
Leonard