81 a trap that when mobs step on pressure plates pistons open up a hole in the ground filled with water 2 blocks deep and they drown and you can collect thier droppings remember to make an exit somehow
83 Gladiatorial arena with lifts for Gladiators and monsters.
The iron blocks are cover stones for the lifts they deploy when the lifts are lowered and retract for the lifts to raise. The 2x2 one has a 2x2 water feed system to move monsters to the shaft from monster farms (haven't made them yet). All can be operated from the box or from the underworks of the arena. At some point there will also be rapid fire dispensers loaded with fireworks, but farming fireworks materials is almost as much of a pita as getting lava from the nether for obsidian.
84 Horse race track/jousting pitch with starting gates.
Dream big. Then again Ive been working on this single map for almost as long as I have had minecraft.
89. I call it the executor, its a rapid fire arrow dispenser array the pressure plates that trigger it also hold the iron door closed. Full diamond armor? It wont make a difference. Just make sure you remember to remove the pressure plates with a pick every time you come home.
80? - Makes a gorgeous decorative block for building
I get so much with a fortune III pick, I can't use it any other way. I also make a block in a different shade or red from NetherWart. These 2 and the dark netherbrick blocks are a great set for dramatic effects