SE is thinking about an instanced dungeon for level 30 and level 50 parties. Well Sony for EQ2 is letting people make their own dungeon. Dungeon making is a popular type of game, why SE hasn't made final fantasy: dungeon tactics yet is beyond me.
Anyways, here's the idea. You have a Dungeoneer class. He's a crafter and he sits around all day thinking, how can I slay all these annoying adventurers who keep trampling my petunias and leaving corpses everywhere? Anyways, he comes up with the idea of building large dungeons with needlessly complicated death traps to keep the riftraft happy and out of his garden. Thus he has one dungeon he can build parts and make additions too. Traps, treasure chests, monster spawn locations, statues of himself, naked women, and himself with naked women. That sort of thing. Then he can put a big neon sign that says "monsters and lonely captured maidens inside" to lure the adventurers in. Those adventurers, us, can then raid his dungeon, slay his monsters, take his loot, free the maidens, and then dance a happy jig on his flowerbed with the moogles playing a festive tune when it's all over.
Obviously as the dungeoneer progresses, he can add better features, maintain a larger dungeon, create monsters with better skill choices and better ai, etc.