dragon egg hatches and you can tame it with meat and you will be able to ride it,also more dragon eggs and dragons spawn in big cave's around your world.
More armor customization. I understand that you can dye leather armor, but in Warhammer Online (lol totally different game) You can dye metal armor, and I think that would be interesting. and very nice for like clans online. to keep track, with colors.
Also, maybe a new mob. They got plenty of pain in the block mobs already, but something new would be nice. the whither beaset and skeketon dont cut it lol
non-timed free version
(I don't want to pay for it)
Never gonna happen.
1. The Mod API
2. More interesting terrain generation. On that note, no extreme hills biomes. Code mountains as a possibility in any non-ocean biome.
3. Ore block slabs and stairs
4. Floating island biome
5. Optifine.
6. A way to force users to use a certain texture pack when access your server.