Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
FBReader - FBReader is an e-book reader for various platforms. Features:
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
Okular - Okular is a universal document viewer based developed by KDE.
Quickreader - Quickreader is a book reading application for the leading smartphones that is combining the solution of two main issues of the book readers namely book reader and availability of books from the leading publication houses.
xchm - xCHM is a cross-platform GUI front-end to chmlib, with borrowed bits from Pabs' chmdeco project.