-Books can be read to increase XP when that whole system gets implemented.
-Dragons would be freakin' sweet.
-XP gives skill such as:
.Sprint w/o affecting hunger
.Double blocks when mining
.Higher punch damage
-Fix the painting on giant mushroom problem. For me when I made my house in a giant mushroom and put a painting on the mushroom wall, the painting was pitch black. When I put it on wood it was fine though...
-Zombie flesh eaten at night temporarily turns you into a zombie.
-Have the ender pearls do something like keep Endermen from becoming aggressive.
-Make saddles craftable!
-NPCs and slightly more common villages. I have yet to find one in 1.8.
-Different minerals would be interesting. Add salt or something and be able to craft more elaborate foods.
At the moment I can't think of a whole lot more, but I think these would be some pretty cool additions.