The first of the tools without durability is a wielded tool whose usefulness cannot possibly be overstated. A staple of life in Minecraft for those who want to do anything advanced, this tool is your faithful friend through thick and thin, and will only be consumed under one circumstance. What am I talking about? I’m talking about....
The Bucket
Constructed entirely of iron, the bucket is one of the most useful tools in the game. Why? Because right-clicking it on a source of lava or water will give you a bucket of water or lava- which you can then place wherever you like. This will let you put water sources in your home, or place lava as traps or protection against monsters- or against other players. What’s more, it will let you save yourself to some degree from incoming lava and water flows- if you think and act fast enough. Very important while mining.
Additionally, the bucket enables you to use cows for a third thing- holding a bucket and right-clicking a cow will fill the bucket with milk. Curiously, no cow ever runs out of milk, but then, there also aren’t any bulls, so anyone who wants to puzzle that out is free to go as far as they like with it. A bucket of milk is a useful item for one reason- drinking the milk will cure any poison or disease you are suffering from. If you’re stuck out in the middle of nowhere and find yourself forced to eat raw chicken and zombie meat, milk is invaluable- because it will let you maintain your hunger bar for a little while without being poisoned to death.
This is far from optimal, since you will find yourself needing to drink milk almost every time you eat, but used judiciously, it just might save your life (and whatever important things you were carrying at the time).
And now the advanced placed tools.
Jack-o’-Lanterns
All pumpkins have faces like a Jack-o’-Lantern, but that’s just decorative- until you find a way to get light inside. Then it truly becomes a Jack-o’-Lantern. The Jack-o’-Lantern is a superior light source to the torch for two big reasons.
First of all, it’s a decorative block. Using it in your home and positioning it creatively in walls can have very pleasant visual effects while still keeping your home lit- possibly inside -and- outside. Second of all, and this is the big one, water won’t put out the light. This means you can place Jack-o’-Lanterns underwater to light the undersea areas, and that you don’t have to worry about an accidental water-flow washing away your light source.
Doors
Doors are almost a basic tool, except that you don’t absolutely have to have them. It is quite possible to get along without doors by placing and digging up sand or dirt in your doorway every day, and it doesn’t take too long. Doors are, however, still useful and, if you don’t care to dig and place repeatedly, can be very important. There are two versions of the door, the wooden door and the iron door. The iron door must be operated by a switch, lever, or other trigger mechanism- but the wood door is opened simply by clicking it once. Doors are mostly useful for blocking animals and mosnters, which cannot open them. Certain addons for multiplayer games will also allow you to lock doors so that only you (or only you and people you designate) can then open them.
The Sign
The sign is usually not very usuful in single-player games, though it can serve as an interesting way of reminding oneself of what one intended to do. Signs are placed on top of blocks as standing board signs (similar to those used by picketers), or they can be placed on the side of a block, in which case they will be hung as a panel on the side. It is possible to use the shape of signs and their placement on the side of a block to make interesting creative structures as well- you should try various things with them. Each sign has room for four lines of text, but the length of those lines is only fifteen characters long. You also cannot edit what you put on a sign- you have to instead take it down and re-place it.
Interestingly, a sign placed on top of a block will be placed facing towards you. Additionally, you can attach signs to virtually anything- including other signs- that can also be placed.