The Ender Chest has a special "teleporting" ability: When an item is placed in it, all Ender Chests belonging to the owner will contain that item. This is not duplication; when an item is removed, it will be removed from all the chests. The items cannot be shared by different players, though; only the player who deposited the item can remove it. Hoppers cannot be linked to Ender Chests.
If a tool breaks while you're gathering resources, you can place the chest, reach in, and grab another.
If you want to send resources back to your house without a minecart system, just place the chest and put them in.
If you're a long way from home when night falls, you can grab weapons and/or armor for defense out of the chest.
If suicide must be used, place the chest down, empty your inventory into it, kill yourself, spawn back home, and grab everything out.
Even though it is mostly Obsidian, it can be mined with any pickaxe. However, it only drops 8 Obsidian if the tool does not have Silk Touch applied.