An good little .cbr comic book archive reader for Ubuntu (or for any other Linux distro at that) is Comix, a lightweight and free image archive viewer by Pontus Ekberg, a computer science student from Sweden.

It has all the normal stuff (as well as a ton more) that you would expect from a comic book reader, including:

• Fullscreen mode.
• Double page mode.
• Fit image to window width, height or both.
• Rotation and mirroring.
• Magnifying glass.
• Image enhancements.
• Both left-to-right and right-to-left reading modes.
• Bookmarks support.
• Archive comments support.
• Archive editor.
• Comic book library.
• Reads most common image formats.
• Reads ZIP and tar archives natively, and RAR archives through the unrar program.
• Runs on Linux, *BSD and virtually any other UNIX-like OS.

It is easily added to your Ubuntu installation by a simple search and install on the term “comix” via your Ubuntu Software Center.

Nifty.

Related Link: http://comix.sourceforge.net/