It seems books that are so old they enter the public domain end up at Gutenberg in eBook format.
I had a friend of mine, Mike Crawford, who died. He refused to put his works in a book and put it up on websites. Well nobody can maintain his website but if he did a book and submitted it to Gutenberg under creative commons his work would live on past him. Many books are on websites for free with advertising or donations to keep them running.