FCEUX is a cross-platform NES emulator. It supports Lua, a lightweight embeddable scripting language. Look, that's not important. What is important is what it does, allowing you never-before-seen control of Super Mario Bros.
Using the mouse, players can wield Goombas and Koopas like some sort of Mushroom Kingdom deity, often with amusing, potentially brain-melting results. This isn't necessarily a function of FCEUX, but looks to be a custom Lua script that lets the player manipulate tiles and enemy sprites for originally unintended Mario manipulation.
We're not sure if this is currently Super Mario Bros. specific, or if we could, say, make Mega Man 2 a hell of a lot easier with our crappy Logitech mouse. It's not currently publicly released, but we hope that's remedied soon. Very cool stuff.
Thanks to Chris for the heads up.