There have been a few NES controller mods, but one modder managed to fit a famiclone inside of his. The mod was made specifically for his girlfriend for her birthday, since she is a big NES fan. Which also means he was a little more thorough to make sure it was right just for her.
The famiclone comes with several built-in games, so many actually that he was extremely disappointed when he couldn't manage to play them all before giving it to his girlfriend. With the controller itself, by using the 2nd player control port you can also use a Lightgun.
He also added a couple extra touches to make sure that the overall look was nice and sleek. He added a backlight to the Nintendo logo and gave the controller a white paint job so it had a newer sheen to it, while still looking old school.