Digipak is a card or paperboard CD case which folds out into usually 3 sections or open up like a book. one section will contain the disc either on a tray similar to ones found in the jewell case or tucked into one of the pouches, another may contain a booklet of the album ( lyrics, comments etc.) and the other may have either the tracklist, comments from the band or album artwork.
The Digipaks with the kind of pouches are similar to the packaging used for Vinyl Records. Nowadays the vintage styles are coming back which may see more Album packaging being in Digipaks.
Ideas: For my design i'd prefer my digipak to have 3 sections. Rather then the traditional CD tray for the CD i'd prefer the CD to be slotted in to one of the panels. This way it is similar to how Vinyl records are packed, which to me seems more of the traditional way of packaging for music. Each panel will contain some sort of image which is relevant to the band or the album. Also the digipak will contain a booklet which will contain lyrics of songs and comments from band members and other media institutions.