Public 'Engine' Folder for Notch

Make the server check for flying, no clip and increased speed.
Add those options to the client, but only enable if the server says it's ok.

Would be generated by fire, be passable, cast shadows, float upwards and disappear after a short time.

Add support for small isometric images, fix the mirroring, render all entities, and don't listen to what the occlusion culler says.

Java API, fully programmable servers, for mods!

Perhaps all floating chunks of blocks should fall down, except for a special block (obsidian?) that can be used to make floating things. Floating islands would need obsidian veins to stay afloat.

Planting a flag (costs gold in survival?) claims an area of land. No monsters can spawn or die from age in that area, and only selected players can build in that area.

eg lava + sand = glass, lava+water = stone (already in, but not generic), water + crops = watered crops, or whatever else.