I actually really like this idea. If some sort of subsection could be added to the database to allow preorder bonuses to have their own database in with the games, I think it'd be pretty awesome.
I'm a bit of a preorder bonus fiend, I don't mind DLC stuff if it's a game I really want to play, but physical items are always preferable, and if there was a database for us, it'd make it easier to tell the official stuff from the fan-made, or fakely-labelled-as-press-kit stuff that we see far too often.
Not sure how easy it'd be to implement though, that's the only problem, since they aren't editions so can't be suggested as such within the database - so not sure if under each game there should be an "Editions" section and "Bonus/Promo Items" section. Plus it'd be very time consuming to add it all (but I'd definitely help out with any of the things I own).
Anyway, great idea imironmann
xx