The “Englines of Creation” by Eric Drexler has been a lightning bolt for me when I read it in the late 80s, and it is great to see it freed for all to enjoy. Nanotechnology has come alive lately in lame textiles or cosmetics products, but the vision of Drexler of nanoscale manufacturing lives on, and is unsurpassed in its bold predictions.
Many authors start to realize that the danger of obsolescence by obscurity is greater to them that the perceived loss of royalties, and they put their books online, sooner or later after publication. Cory Doctorow is one of those who do it simultaneously with his science fiction books, which can be purchased in paper form, or downloaded electronically at the same time. Stephen Wolfram also very positively surprised me when just a year or so after the publication of “A New Kind of Science” he put it online for free.