I really would like to try and add a town and travel phase to the game, which I think could be easily done and also a overland map to quest around in.
I also would like to add more men / dwarfs / elves to the game as "monsters" to face and have a castle / outdoor locations to adventure.
Definitely. I think the simplicity of the system should help in adding things pretty easily.
I'm looking forward to seeing how the Deeper Dungeons expansion handles some of this...