ImageBrowser
From MobileRead
ImageBrowser can be obtained at http://homepage.mac.com/levanj/Cocoa/ and then scroll down or search on page for it.
This is really a tool for looking at images but the latest version has added CBR/CBZ support. This means it will support graphics novels also known as comic books or Manga.
It can also convert a set of images to PDF format.
This program runs on MacOS X.