I'm probably preaching to the converted, but Gutenberg has a ton of free scifi in multiple formats. Anyway, figured it was worth a reminder.
http://www.gutenberg.org/wiki/Scienc...ion_(Bookshelf) is the main Scifi link, and the authors are listed alphabetically. yes, there are lots of known, and even still living (eg Cory Doctorow who sells his books but also lets people have them for $0).