For my Australian readers, Project Gutenberg Australia and Free Read make available books that are in public domain in Australia, but are not available on the main Project Gutenberg site because of the United States' ludicrously controlling copyright laws. These would include many classics from the early 20th century.
Note: These books are only legal for people residing in Australia or other countries where public domain begins fifty years after an author's death. For people living in the United States, or other countries which have legally determined that authors may need their royalties even after they've been mouldering in the grave much longer, it is illegal to download these books. I'm not a lawyer, so I can't even say whether it's legal for Americans to read them online.
However, if you feel like quietly protesting ridiculous copyright restrictions, go to your public library and check out a book by an author too dead to enjoy his or her royalties. It's completely free and legal.