Maybe one day, Iphone killer Uphone works much better than Iphone5, but only accept BTC payments ...
these are coming. milk toad, or whatever that site is called has a model that seems to work.
there are other products which could only be sold similarly. your iphone killer comes to mind. manufacturer knockoffs that violate intellectual property would not be able to be offered anywhere else, but with an anonymous marketplace using bitcoin as the payment a lot becomes possible.
knockoffs of designer brands like prada, gucci, coach, and others sold on the market will generate interest in bitcoin with a segment that would otherwise be oblivious to bitcoin.