I wanted to read Manga on my Nook and began reading how one might go about accomplishing that. A search showed one or two programs that could do this but neither were 'final' at this time.
So, being the stubborn person that I am I fretted over this little detail until I came up with a simple, quick way to do this for any eReader!
Here are the steps I took:
If your manga isn't already in a .zip file you will need to do this first. I use winRAR which you can download here: http://www.rarlab.com
Once zipped (or if it was a zip file to begin with) simply change the .zip extention to .cbr
(Comic Book Archive files are structured exactly like other archives using the same type of compression; only the file extension differs. For example, a CBZ file can have its file extension renamed to ".zip" and can then be opened in Microsoft Windows by a handler such as WinZip by double-clicking it. A CRB file may also be renamed to ".zip" and visa versa.)
Import the file to Calibre and covert to desired format.
Load into your Nook or Kindle and BAM! Your manga is now readable on your eBook device.
That will get the manga easily on your machine, but if you a touch OCD like me you might want to use Calibre or even Sigil to edit your epub manga a little further. By adding cover art, meta data and so forth.
Hope this helps some of you who have been thinking of reading a few Manga on the go but weren't sure how to proceed.