CBZ, the MP3 of Comics
Digital music and, more recently, digital video and digital books, have changed the way we consume media. Comic books are no different, and with the advent of tablet computers, digital comics are becoming more and more popular. If you don't have a tablet computer, however, viewing CBR (or their zip compressed counterpart, CBZ) files is as simple as installing a CBR reader and downloading your favorite comic.
Many comic book readers are available for Linux. A quick Google search will turn up programs like Comix, ComicMaster and Comical, all of which display digital comics quite well. Another search likely will turn up some free comic resources, like the one shown here: Cory Doctorow's Futuristic Takes of the Here and Now. If you miss the comic books of your youth, or if you still enjoy them on a regular basis, you owe it to yourself to check out CBR/CBZ files.