One request I'd like to make is to not make overly expensive like some publishers tend to do with collector's editions of their games. Put stuff that's cool, but don't add in a lot of junk just for the sake of making a big, fat collector's edition. The way you went about with the collector's edition for The Witcher 2 was perfect.
I'd say an Artbook, Soundtrack and Making of, are a given. If you're gonna put some sort of 3D figure, please make it something classy like Geralt's marble head bust/the witcher medallion rather than some crappy, oversized toy made out of plastic. Also, I'm gonna request that you not put stuff that people can get from elsewhere, like The Witcher comic or the novella's. These are things that an average Witcher fan already has, or get for himself from Amazon. You should rather put stuff that is unique and unavailable elsewhere, like the Geralt marble bust.
Couldnt agree more!