Terrain- With the next map, varried height in terrain should be implemented. Instead of ridges, there can be full cliffs to hide in. There could be a base sea level as well.
One would have to flatten things out to build larger objects. (Yes I know this sounds like Wurm)
Hidden Crafting- Say I have a bottle of blood (which would be awesome), and I right click that on yarn, it should turn red, then brown (Blood is made of iron and that rusts etc)
So in the end, I have brown yarn. If I make a toga with that yarn, it'd be brown also. This could be used by a sect of monks. Other things could be hidden by someone and no one would know but him.
Dye Pots- You go and get a bunch of berries, put them in the pot, and wait. In the end you have a blue dye. Well you put the blue dye and say a red dye, in equal ammounts, you get a purple cloth if it'd dipped. If you put 2:1 blue and red, it'd be more blue. If the dyes had RGB values, that when added together would change the RGB of items that'd work to create many combinations. A yellow dye, plus a red dye would make orange, but if you added 3:1 yellow and red, have it come out obviously more yellow. People could also experiment with say white, green and orange to see what happens.
New metals- Further out rings with mines could hold different metals in them. Of course not all the tiles in the mine would hold this metal. The northern regions might have copper, and the east tin. They'd have to trade so someone else could get bronze. Weapons like these could be more standard than a steel sword, making steel more valuable.