Some interactive NPC's would be nice, ones that you could possibly trade with. A possible trade screen where you can put up your items for some of theirs and if the values equate with another or you are above you can buy their material, and or you can steal and have them go hostile on you.

Dirt = 1point
Obsidian = 500 points

Trade 500 dirt for 1 obsidian block. Something like this, but the NPC's will have a small amount of items, like 2-8 of obsidian maybe a diamond or something to trade.

Yer, ive heard if you be friendly to them they give you stuff, but if you attack them they will all come and kill u :O

that would actually be a good thing about them but it really depends what the attack damage is on but that would be nice

Yea, friend just sent me an image of what has been added, I guess they have a new mode where you only get 1 life. When you die you have to delete the world. I think it is called "Hardcore".