Tips, Tricks, and Traps in Minecraft

Post some useful tips, tricks, and/or traps you've learned from your adventures through minecraft. I'll start this off by posting a few I've learned such as...

The water ladder:

Important note: the water must be placed on the south or west sides of the ladder for this to work.

The secret door:

Important note: because of the updates you have to get rid of the blocks fast and replace them with the door as soon as possible, otherwise the picture will come off the wall.

Bucyruss's mob tower:

This trap works GREAT in single player if you make it so that the mobs don't spawn anywhere else, unfortunately it doesn't work so well in multiplayer.

I'll keep it at this for now and add to the thread later in order to keep this post from getting too big.

Here's a good video on how you can use redstone dust on doors (skip to about 2:20 to get to the tutorial):



He also has some other redstone tutorials if anyone's interested

An explanation on grid mining (this guy has three in between but I usually have two to try and not miss anything):



and a fast and compact arrow launcher which can be used as a great mob trap: