System: Nintendo Entertainment System
The Legacy: The first major NES peripheral released by Nintendo that wasn't a light gun, the Advantage had an arcade-style joystick and fat, red buttons to mash to your heart's content, or until you reshaped your thumbs. That said: Who needs to mash buttons when you have twin Turbo buttons (and dials to tune how much 'Turbo' you wanted) on this thing?
But the Turbo modifier became more of a third-party accessory business; this wasn't really Nintendo's style. And the joystick? It mostly stayed in the arcades, and on third-party controllers as well. That said, this thing does have a very real pop culture legacy that lives on through today: At the end of Ghostbusters 2, the NES Advantaged is paired with a Sony Walkman to control the Statue of Liberty.