This looks interesting for anyone's who got a home library of educational PDFs-
The National Academies Press Makes All PDF Books Free to Download
We still have to pay if we need a hard copy though.
WASHINGTON -- As of today all PDF versions of books published by the National Academies Press will be downloadable to anyone free of charge. This includes a current catalog of more than 4,000 books plus future reports produced by the Press. The mission of the National Academies Press (NAP) -- publisher for the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council -- is to disseminate the institutions' content as widely as possible while maintaining financial sustainability. To that end, NAP began offering free content online in 1994. Before today’s announcement, all PDFs were free to download in developing countries, and 65 percent of them were available for free to any user.
We still have to pay if we need a hard copy though. The hard copies can be VERY expensive. Here's hoping everything remains free for download for ever.