Many research libraries are contributing scanned images of works outside of copyright. Read online or download in various formats for various e-book readers. Download options include PDF, EPUB, Kindle, DAISY (ANSI/NISO Z39.86 open format), and others.
Books, manuscripts, periodicals, images, scores, etc. spanning a wide array of disciplines from Bibliotechque Nationale de France with materials reaching back into the 17th Century. Materials can be downloaded as PDF, JPEG (individual pages) and TXT.