Stuff it'd be easy to add:

Guy who cares about which mobs you've killed -
- tied into the repbuy system
-Y coordinate decides which mob he cares about
- bumps your DEF rolls by 1 when you fulfill

Chatty npc -
- not tied into repbuy
- just gives you a hint based on Y coordinate
- might spend too much charspace?

Needy guy -
- bump 'em to give them one gold, receive one rep

Stuff it wouldn't be easy to add:

Hidden stuff -
- concealed traps which fire (unless revealed + destroyed by a search roll)
- basic trap could do damage (but never kill)
- others could poison, or scare you out of the cave, or destroy minor treasure around it
- hidden routes and minor treasure/hp pots

Enemies that move -
- has to have accuracy 2
- move towards you whenever you perform a kill