ManyBooks.net has many nice FREE ebooks. Classic, public domain and newer CC licensed ones too.
Including a good selection of modern Sci-Fi books, Cory Doctorow’s titles and others.
Cory Doctorow’s titles on file there: https://manybooks.net/search-book?search=Cory%20Doctorow
Nice site, recommended.
@design_RG That's cool. Big fan of Little Brother.
I will say though, I really dug Project Gutenberg as a kid. Is this site better?
Feedbooks also has some free, Public Domain books. FBreader has it on as a library source also.
http://www.feedbooks.com/publicdomain
The number on the columns on the left in the image are some of the available free ones.