Luigi Cyclone

In Super Smash Bros Melee, the Luigi Cyclone is Luigi's Down Special Move. It is similar to the Mario Tornado. The attack makes Luigi spin around wildly. It can be used as a vertical recovery move by button-mashing the B button, but this only works after a jump because the move carries Luigi's momentum with it. If used while falling, this move will just slow Luigi's fall. It is generally perceived as being very difficult to to get the full height due to the number of times the player needs to push B button during the animation. This move does not put Luigi into a helpless mode, so you can use the Super Jump Punch after. It is a multi-hitting attack.

In Super Smash Bros Brawl, the Luigi Cyclone can travel across the stage quicker with it, but there seems to be less control, and it is harder to trap the opponent within it. The vertical recovery distance is now easier to perform than its Super Smash Bros. Melee counterpart. This move gains higher total altitude than his Super Jump Punch. If the Cyclone is used at the peak of Luigi's mid-air jump, it is much easier to gain height.

Pressing Down+B right before Luigi touches the ground allows him to instantly use the move again. 

Origin
Luigi Cyclone is a clone to Mario Tornado which is likely based on the Spin Jump that originated in Super Mario World and the Tornado Jump from Paper Mario. In Super Mario Galaxy, both Mario and Luigi have a spinning attack very similar to Mario Tornado and Luigi Cyclone. The spinning attack from Super Mario Galaxy gave them both vertical recovery when used in the air, just like Luigi Cyclone does and Mario Tornado did, although in Galaxy the spin acted more like a double jump.

Trivia
If it is timed right, Luigi Cyclone can get rid of a tornado that Luigi is in on Hyrule Castle.