Project Gutenberg (via Learn a Language) "is the place where you can download over 30,000 free ebooks". They've got the complete text for numerous books that are in the public domain.
And their books cover lots of different languages. The languages with the most books are Chinese (405), Dutch (477), English (26,942), Finnish (527), French (1,593), German (675), Italian (238), Portuguese (426), and Spanish (284), but there are plenty of others there as well. As with LibriVox (which serves up audio books for books that are in the public domain, as covered here), because these books are all in the public domain, they tend to be old, so you probably won't be getting the most recent lingo in any of these languages.
Speaking of LibriVox, Project Gutenberg is in fact working with LibriVox (in multiple languages) and LiteralSystems (almost all in English) to get audio books of their ebooks. Go to Project Gutenberg's audio book page and search for the language of your choice to see what they've got. For English learners, they've also got a bunch of computer-generated audio books, but I'd stick with the human-read audio books if you can.