I know there's the usual things like extra content, videos, bonus tracks etc but I think the CD / vinyl form itself is another got medium being underused.
Take the Liars' latest record, I pretty much bought the limited edition for that fold out sleeve. It's awesome.
And I spotted these guys today, called ACDSleeve (great name) - they're doing some great things too with BigScaryMonsters:
Do these things matter to you? Do you have limited edition one off's you adore? Would it get you buying more records instead of downloading them?
First person to mention Spiritualised gets a yellow card...