Mr.X] added support for four controllers to his Super Nintendo (Google translated) by internalizing the multi-player adapter. In the video after the break you’ll notice that he also added some bling to the case by positioning the power LED beneath the logo and adding a two-digit display. There is a switch on the back that allows him to choose PAL or NTSC standards with the current setting shown on that display. While most people are going with emulators, [Mr.X] ended up with a custom piece of hardware with a clean finish.

http://hackaday.com/2010/07/20/4-player-snes-and-more/