I'll continue skipping around until the end (which is very close!)...
I have been aware of Project Gutenberg for many years, and use it occasionally. World eBook Fair was a slight disappointment - looks like it is only free once a year. Granted, the $8.95 membership fee is not much, but it is not free!
LibriVox was much more interesting - it has about 800 titles and would be a good resource for high school and older to listen to, rather than read, a book.
The most intriguing find was Wikibooks. According to their site, it is, "a free collection of open-content textbooks that anyone can edit". What a world of information out there! Always, more than I had imagined.