Google just announced that it will now allow users to download over 1 million public domain books in the EPUB format. Google had already made this archive available to some of its partners, including Sony and Barnes and Noble, but until today users weren't able to download these free EPUB texts from Google directly. Google will continue to make PDF versions of these books available for download as well, but users with eReader's will find the new EPUB files far more useful.

If you don't have an actual hardware eReader but still want to read these EPUB versions, you can install Stanza or a similar desktop reader to read these books.

EPUB: The One eBook Standard to Rule them All

EPUB is a free, standardized format that almost every hardware eReader or desktop software understands. Amazon's Kindle, however, cannot read EPUB texts without using some intermediary software that converts these books into a format the Kindle can understand. While there are a few competing formats, EPUB has turned into the de facto standard for eBooks. Some vendors, like Sony, wrap a digital rights management (DRM) solution around these books, but others just publish completely open, non-DRMed versions of their books. The EPUB files from Google Books will not be locked down by a DRM solution.

It is important to note, however, that these EPUB files were run through an optical character recognition (OCR) system and weren't edited afterwards. While this software has greatly improved over the last few years, there are still quite a few mistakes in most books. This post on the Google Books blog explains the conversion process in more detail. The PDF versions of these books don't suffer from this problem, as they are just copies of the actual pages. This also means, however, that these PDF files are far larger and that users can't, for example, adjust the size of the books' fonts according to the size of their screens.