Steel and Rust

Steel Ingot and Blocks:

steel ingots are created by smelting a iron ingot. Then by putting 8 steel ingots into a crafting table in a chest pattern you create a steel block. with a steel block you can create stairs and slabs and also a  corrugated iron block, which also can make slabs and stairs.

Rust:

All the blocks mentioned can also be rusted by placing it next to water. This would work like the coppar block but with water. This would be a great building block that definitely would fit into minecrafts new "Caves & Cliffs Updatte".