Firstly, there are some conventions of packaging an album that I don't think should be broken for numerous reasons, mainly to do with the ability for a store to sell the album well. Sure, we can have the argument that most bands no longer rely on record stores as the main means of selling their music, but if a musician is planning on selling any of their albums in a store, here are some things to consider:
The shape of your packaging: if your CD case can't fit into the store's display shelves/racks/bins, then most likely your case will end up in some dusty corner, badly displayed. It astonishes me that so many artists don't see the logic of making their packaging fit within industry standard guidelines.
The visibility of your spine: sure if you've got a best-selling CD your case is going to be front and centre face out prominently on display, but even the most popular CD is eventually relegated to the bins. This means that your best bet of having someone pull your music out of the masses of other music is to make the spine wide enough to be seen AND to put your name and the title of your CD on the spine. Simple right? The best way a band can avoid this issue, is to make sure that they never release their music in a single pocket cardboard sleeve. Those suckers never have a visible spine and they look like shit. Fact.
Get a Barcode or a CAT number: again, this is simple stuff - if you can't be arsed registering your album for a barcode, get a catalogue number (either from the company distributing your music, or if you're distributing it yourself, just make something up) and place it on both the album and the disc itself. "Oh but Luci!" I hear you cry, "We're self-published! Why would we need a catalogue number?" Well dear reader, it's because a lot of record stores separate the disc from the case - if the disc and the case have a catalogue number, it makes it easy to be sure you are putting the right disc in the right case. This is especially important if either the disc or the case doesn't have your band name and your album title on it.
Unless you are mega-super-famous, don't be a tosser; put your name and your album title on the cover. It doesn't have to scream your name, it just has to whisper it at the very least. If that's too cliché for you, at the very least, sticker your cases so that the information is there when it's being displayed.
Finally, and this is one I'm a bit more forgiving about, seriously consider whether you go cardboard over plastic cases. I know plastic cases are worse for the environment and also cost a bit more, but cardboard cases fall apart really easily and they don't protect your music half as well especially if you've got a set-up where the discs need to be pushed and pulled in and out of a tight wee pouch without the protection of a paper sleeve. Think about how vinyl is packaged - LPs are usually put into a paper slip before they're slammed into the cardboard sleeves. Protection first! A nice solution to look into is the digipak format: having a cardboard outer with a glued in plastic CD tray (like this one,this one, or even this one).
Also, if you are getting cardboard sleeves printed for your album, talk to the printers about the kind of card stock they recommend you use. If you print on certain stocks, when folding and scoring the card into your case, the card will crack and tear the printed image. Printers know which stocks hold up to being brutally folded and scored and are more than happy to share their knowledge. Ask them!
It pays to remember that with the advent of digitized music downloads, if someone is wanting to buy a physical copy of your music, they probably are buying it for the aesthetic delights the packaging holds/nostalgia and ergo they will want it to last - both the physical packaging and the disc itself.
That's about it - what do you think? Do you disagree with me? Or are there other things that bug you about music packaging?