There are a few things they have that are hard to find elsewhere, like the gem Nature of the Beast starring Lance Henrikson and Eric Roberts. It's a blast of a film --I'm not going to give anything away, but when I had Amazon Prime for free for a while, it was the only place that had that film (sadly couldn't even find a decent bitrate version of it sailing the seas).

Same with the director's cut of The Lawnmower Man. There was only one Russian site that seemed to have that version but in 240p or so, making it extremely difficult to watch. Amazon was the only one that had an HD version of the director's cut.