Boomerang
The Boomerang is an item that make its appearance in some of the e-Reader levels of Super Mario Advance 4: Super Mario Bros. 3. When thrown, the blue boomerang defeats any enemy it touches before returning to Mario, who much catch it using the B button if he hopes to re-use it.
While a few Japan-only levels featured blue boomerangs, only one of these was made available in other regions: the World-e level Slidin' the Slopes. Near the end is a Boomerang Bro. with a blue boomerang that is dropped when the enemy is defeated; the player can then pick it up and use it for the remainder of the level, though it disappears upon completion, much like the Goomba's Shoes. The boomerang will be returning as a power-up in Super Mario 3D Land.
There was also an e-Reader card released only in Japan that uploaded a boomerang to the player's inventory; the item worked the same way as the blue boomerangs.
