Here is cbrpager.
A no-nonsense, simple to use, small viewer for cbr and cbz (comic book archive) files. As it is written in C, the executable is small and fast. It views jpg (or jpeg), gif and png images, and you can zoom in and out.
NB it uses GTK+ and you may have to install a bunch of gnome stuff to satisfy dependencies.
[updated to include an icon and relevant desktop entry so that it will (hopefully) appear on the menu of WMs]