Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
Greenstone Digital Library - Greenstone is a suite of software tools for building and distributing digital library collections...
LibriVox - free public domain audiobooks
Koha - Koha is the first free and open source software library automation package (ILS).