Anyone remember the old strategy game "The Horde"? You would have a certain amount of time/money to spend sowing, ploughing etc. and basically preparing for the annual horde of monsters invariably invading your farm every spring. Depending on how well you protected your crops, the farm grew, yielding more cash, better weapons to keep the monsters at bay, etc. A solid farming system might well change a roguelike into something... similar, but different. Who's got the time for dungeon crawling, now that harvest time is coming?
* Setting traps: might be fun, and doesn't have to be too complicated, and probably would fit well with a "regular" dungeon crawling rl. Other crafts might be interesting, as well, but I can see how it would quickly be boring to make bread, for instance. Just imagine the equipment you'd have to carry around to shear corn, crush it, mix with water, yeast and spices, make a fire and bake it. But I would like a game where there's more interaction with the landscape -- digging for buried treasure or maybe even using a dousing rod, clearing overgrown bush, building and tearing down walls...
* Working with servants/pets/henchmen/allies. Maybe a system where more complex orders can be given, and different servants are better differenciated. Like asking a servant to guard a door or patrol an area (and recognising this particular person's voice when he shouts as someone/-thing enters the room), or hiring certain allies for certain tasks (some servants/allies might act as scouts, others as healers). If you don't want to implement a complex alchemy system, you can always create friendly monsters who will mix potions for a fee, or if they like the player. One could include skills like "agitating" to sway crowds. For a game with long term ideas like farming, I also don't see why the player shouldn't have children, that might take up adventuring when their heroic parent pass on in some dungeon level N.
* More randomness. It could be an interesting task to try and make exploration more exiting, by randomly determining stuff like architectural style and other quirks of different places. Is the village an anarchistic commune protected by the villagers (they'll fight if one of them is attacked), or maybe there is a small barracks with soldiers (villagers will generally flee from violence, but guards will emerge)? Is there a village elder or other heroic npc? Distinguishing traits (and possible sources of quests), such as a mineral source, a temple, a casino, a haunted forest, a holy ruin? What is the main source of income/food? Farming, hunting, domestic animals, scavenging, craft and trade? (would effect what kinds of equipment/food the player can get hold of) etc. There also shouldn't be anything wrong with randomly generating some common monsters and/or herbs at the beginning of the game. What is the popular steed of the land like? Slow or quick, obedient or wild? What does it eat? Anything from three-legged, grass eating brutes to quick, zebroid carnivores could emerge. What are the weaknesses of vampires? Maybe fire in one game, water in the next, and so forth. Also, there would be nothing wrong with randomly generating artifacts, maybe even complete with a small legend.
And so forth.
My guess is that if you take this far (too far?), you'll have to add lots of text for flavor and explanation, which will suit some players better than others. But it could certainly be a new take on random/coherent content. I've always liked ADOM for the heavy emphasis on mood, but in the end, it's kind of boring to do the exact same quests over and over, every game.