There are few possibilities, you should choose which one suits you the best. Most popular comic book readers are:
YACReader is very light and easy to use, and it works on Windows, Linux and MacOSX. It's a very nice comic reader with some interesting features. It comes with YACReaderLibrary, a comic collection manager.
Comic Rack is probably the best choice, as it offers many useful options, is still under active developement and available in many languages.