Ah, yes, the Priceless Ming Vase. That is mass destruction for you.
Others of my favorites:
Scarabs from SC. Everything explodes.
The Imperialist from Metroid Prime: Hunters (just because I like the name
)
And while I'm talking about Metroid, I'll mention Quadraxis from Metroid Prime 2. That thing
is a weapon.
Nightmare's Soul Calibur from Soul Calibur II. BIG FREAKING SWORD FTW.
Plasma power in Kirby games. Especially Kirby: Air Ride where it enabled you to take out everything in front of you with one shot.
One of my all-time favorites, though, has to be the Ice Arrows in Legend of Zelda: Ocarina of Time. They're so awesome and yet so...utterly useless...