Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
calibre - Ebook manager, viewer & converter
Qiqqa - Qiqqa is a free research and reference management software. It can be used in many organizational projects from the academic to the personal to the business endeavor. Read more about Qiqqa.
FBReader - FBReader is an e-book reader for various platforms. Features:
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.