I have two that I think were great...
First, at the Gamestop launch tournament, Fox vs Fox we're tied with about 5 seconds to go... I drop through a platform, and land on top of a rolling crate, right next to the edge. He didn't see it was a rolling crate and had started charging up an attack, only to hit the crate I'm on top of, have it bounce back from hitting the edge, and hit him about half a second later, sending him off the screen as the clock ran to 0.
The second happened tonight, on WiFi with anyone mode... It was a 4 player match, and 3 of us went into sudden death, me(Kirby), a Snake, and an Ice Climbers... The sudden death starts, Snake tries to attack me, I jump over it and begin waiting for an opening. A couple seconds later, the snake uses side-B, and I see an opening, so I jump down from above him and use a bair. As I'm falling and about to attack, he turns the missile so it hits at his feet, and sends us both flying to death as the Ice Climbers watch from the other side of the level