This is quite a big suggestion, please don't point out that it is a lot of work and Toady has more important things to do. I just wanted to throw the idea out there and maybe discuss it.
I want to have a tool for dynamically generating worlds in as much detail as possible as a setting for tabletop role-playing games. Dwarf Fortress already does this better than any other software. A few relatively minor changes to the interface and game flow could make it the perfect tool.
Basically I am suggesting a new mode for DMing and storytelling within the DF world. The user would require access to all legends, preferably in as simple a way as possible during play, eg. like the fortress mode access you have to each characters background and skills and personality. The user would also need the ability to spawn creatures and items into the world, to travel instantly anywhere, and to change various settings and variables like attitudes, wounds, date, time, etc. So basically a god mode for adventure mode, or a world roaming version of fortress mode. Kind of a hybrid of the two modes with a few extra features.
I think that the development goals for the near and medium future are all very much in line with this new mode, especially the loosening of single site restrictions in fortress mode. It would also require some tweaks of it's own. If this idea interests people, I would love to see it at least kept in mind as a possible later development.