Customization is central to Minecraft, and an upcoming update will make that aspect even more robust. With the 1.8 update, you'll be able to directly impact aspects of the terrain generator, from aspects like "Biome Depth Offset" to "Depth Noise Component."
That sounds confusing enough to appeal to the most ardent block-building fans, but Mojang will supply seven presets to show off what you can do with the tools. One will have water all the way at the top of the map, and another will bring back floating islands. The customizer includes 16 sliders in all, but you could also enter values directly for an even more obsessive level of precision. Check out the preview below.