Mob Attractor

Mob Attractors are Redstone items that when turned on will lure all Mobs in a 16x16 square to the attractor. Passive mobs, including tamed mobs, will run away from it. It can be turned on with Redstone or with an activator. If two attractors are combined on top of each other, the result will be a larger version with twice the radius.

Crafting Recipe
This will result in 2 Mob Attractors.

Use
Use it to attract all Mobs in an area into a trap (ex. Mob shredder or deep pit) to keep your house from being invaded all the time and can also save Villagers from Zombie sieges. You could also use it to herd many passive mobs to one place.

Trivia

 * Creepers will not attempt to blow it up when it is active.
 * Endermen can steal Mob Attractors when they're turned off.
 * Cats will not sit on it, because of the sound it gives off.
 * They also won't sit 5 blocks near it, and if you tell them to sit, then they will hiss and get out of the 5x5 square.
 * If they can't get out, they will hiss all day until they do.