calibre - Ebook manager, viewer & converter
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
FBReader - FBReader is an e-book reader for various platforms. Features:
ReadOut - ReadOut is a text to speech conversion app by Flying Phoenix that offers features to enable you to import text from a variety of different sources to convert it into speech in various languages right on your mobile phone.
Foliate - A simple and modern eBook viewer.
Cool Reader - Fast and small cross-platform eBook reader for desktops and handheld devices