The SNES controller is one of my favourite console controllers. Unfortunately, the proprietary connector makes it difficult to use with newer devices. Thanks to the Teensy USB dev board, you can get the best of both worlds: a great and sturdy game controller and USB connectivity so you can use it with modern consoles or with your PC.
A long time ago, I used to use an old SNES controller connected to an adaptor that connected to the old serial port on one of my ancient PCs -- it was perfect for emulated games. Now, the Teensy USB board can do something similar, but it requires a little more hand-on time. You'll need some soldering skills for this project since you'll need to strip some wires and reconnect the controller's guts to the Teensy before you can use it.
The whole process isn't too difficult, but it does involve opening up the controller and rewiring the inputs to the Teensy. Instructables user johnberkert walks us through the process from start to finish at the link below. Sure you could just go out and buy a USB gamepad, but if you want a really great -- and cheap -- controller for your retro gaming PC or your iPhone or Android, check it out.
SNES + Teensy = USB/PS3 Gamepad [Instructables]