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calibre - Ebook manager, viewer & converter
Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.
FBReader - FBReader is an e-book reader for various platforms. Features:
XenForo - Intuitive. Social. Engaging. Fast. XenForo brings a fresh outlook to forum software.
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.