A dungeon made to showcase the ideas described in the "Improving Dungeons" thread in the suggestions forum of Minecraft Forums. This dungeon is huge, especially compared to the current dungeons (which this would replace), although I won't tell you what's in it. It is a whole lot bigger than what you would find if the ideas were implemented into vanilla, but it, in my (and my building partner's) opinion, is really, really fun. Grab whatever you want from the chests in the house, change to the difficulty you want (give it some time, to let monsters spawn), and get at it!
Link to thread: