Here are a couple of tricks that you can do with torches on Minecraft that you might not have been aware of..
Break sand and gravel stacks
If you need to break a stack of gravel or sand, first you need to take out the bottom block. Then replace it quickly with a torch and the rest of the stack will fall down and break up.
Build on torches
Although blocks break when they fall on a torch, you can actually build on top or to the side of them. They act as a support strut and are treated as another block. However, they allow the player to pass through them.
Grab a breath under water
If you are mining and accidentally open the floodgates, or perhaps swim too deep, you can use a torch to create an air pocket. This will not last for long, but long enough for you to grab a quick breath. Get right up against the torch when you place it, or it won’t work.
Generally, torches can only be placed on solid, opaque blocks, but you can also place them on the following:
soul sand, packed ice, monster spawner, snow (must be at least 8 layers thick), on top of fences, glass, half slabs and cobblestone walls and on top of upside down stairs.
Just Dudzy 