I've just thought - it'd be nice to be able to add more generic guys to the list, just in case you want more than a handful of different kinds, especially since most of them have pretty specific behaviours.
At the very least, being able to pick a tile/cset for an otherwise completely stationary guy would be nice, though allowing them to always appear on OW/in caves, no matter the setting for the dmap, or even just allowing animation frames (whether it's flipping, like Fire or just multiple frames like Fairy) would be ideal. Maybe even making the dungeon d-map 'you hurt me I shoot you with fire' behaviour tied to the guy themselves (or at least overrideable with some kind of a flag on the guy).