This story is proof not all of these stunts have to be spiteful in nature.
A video game developer in Australia had no ill will toward his current employer, he simply felt it was the right time to start his own game development company. So what better way to soften the blow than to do what he was paid to do?
The man created his own modified version of Super Mario Bros which his bosses had to play that explained his decision to quit. It was creative, thoughtful, and done with tact.