calibre - Ebook manager, viewer & converter
Total Commander - A Shareware file manager for Windows® 95/98/ME/NT/2000/XP/Vista/7, and Windows® 3.1.
FBReader - FBReader is an e-book reader for various platforms. Features:
XYplorer - File Manager for Windows
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
Double Commander - Double Commander is a cross-platform open source file manager with two panels side by side.