You know what i want? I want notch to add Aether and more Nether mobs.
After playing for some time, the Aether doesn't really feel like part of Minecraft.
The dungeon system and accessory system should definitely be incorporated, though.
See, the ORIGINAL suggestion could have fit in Minecraft, with the sheepuffs, pigasi, aerwhales...
but now with Valkyries and Fire Bosses and giant sliding stones, no.