The //set randomization function is amazing!

It'd be even more amazing if //replace, /replacenear, and a few others supported it. :)

Any you want in particularly? I am being choosy because the framework behind the randomization slows down the process a fair bit, so I have to make two versions of each command that supports it: a original fast one and one with the framework.

//replace would be top of my list.

I used //set to make a "swamp" biome by filling with randomized mud, water, leaves, and dirt/grass blocks. The result was pretty nice when coupled with a canopy of leaves and some lightstone here and there. //replace would have made it easier to look contoured.