Home-made Fortress that only needs water? *Tick*.
Anyone miss the Tel Uvirith tower, people made some great mods for it too, like one expanded to have a massive dungeon and a giant treasure room with armor and guards. I just wish that you had the option of hiring people to guard your tower against invasion and silly stuff. It was a cool concept for Morrowind, and probably has no place in Skyrim, but homes with dungeons where you can DISPLAY your loot would be cool, anyone with me on this?
I hope that with Radiant AI, that treasure hunters or thieves will try to loot your dungeon (and you can pursue them). Or perhaps you could merge ("match records") with other players and try to loot theirs.