I converted into EPUB and MOBI the second editions of the two books:
Richard M. Stallman
Free Software, Free Society: Selected Essays of Richard M. Stallman, Second Edition
Sam Williams, Richard M. Stallman
Free as in Freedom (2.0): Richard Stallman and the Free Software Revolution
If you visit the above two URLs, you will find the recipe to produce the e-books from the source files available from the FSF, which authorized me to "spread the news" (they are going to publish the EPUB on their website too).
Note 1: the above e-books still need some polishing. Please comment here or send me an email if you find out issues you think should be fixed.
Note 2: you can download the PDFs of the two books directly from the FSF site, the relevant links are provided in the above pages.