Maybe dungeons could be bigger/nicer? Whenever I come across a dungeon, it's just the normal loot(rotten flesh, horse armour, maybe once in a while a music disc). It could have some traps or tripwi...
Maybe more gems/ores? Copper, steel, and tin would be nice. Cave mobs would be cool too. Like Cave Ghosts, or Miners that trade ores with you like an underground villager.