If you want to use original NES or SNES controllers with your Raspberry Pi, you could use SNESDev, which I have written about some weeks ago. SNESDev makes use of the user-space input module and simulates a virtual keyboard. This means that button presses on the controllers are mapped to key presses on the Raspberry. Another approach for interfacing a controller with the Raspberry from the software side is to use a specific Linux input driver. Marqs has adapted such a driver to the Raspberry Pi hardware and made it available to the public.
You already might have heard of the Raspberry Pi. It is a credit-card sized PC from the Raspberry Pi Foundation and is going into mass production and distribution these days. There is a huge demand for “the Pi” and the first orders are limited to one per person. A few weeks ago I got my Pi delivered and started working on what I would describe as “universal console”. In this post I describe my initial thoughts about this project and present an adapter that allows you to use SNES controllers as input devices for the Raspberry Pi.