Comic Book DS V1.0 Released!
Finally something good to read comics on-the-go!
Francis Bonnin has released just yesterday a great homebrew, ComicBookDS. It can take folders, RAR, Zip, CBR (ComicBook RAR) and CBZ (ComicBook Zip) files, and generate a file you can use on your NDS. You can view them in a few modes, along with deciding if you want to show them horizontally and vertically, and you can even set the backlight on the fly!
You can find more info here, and a download link here