With a few quick modifications, you can fit a bluetooth module into a classic NES controller.
Jamen Lang always wanted a Bluetooth Nintendo Entertainment System (NES) controller. When Adafruit recently announced its BlueFruit Bluetooth controller, Jamen jumped at the chance to implement the controller he'd been dreaming of -- finally.
The BlueFruit is a fairly small Bluetooth human interface device (HID) device. At 23 mm x 39.6 mm it can actually fit inside many devices. All you have to do is supply power to it, and it can be seen as a Bluetooth keyboard with 12 buttons preprogrammed in. Of course, you can program your own as well. Jamen observed that this would be perfect for his Bluetooth NES controller with minimal modifications. He ordered one, as well as a 1,200-mAh battery, which he acknowledges is overkill, and began working.
He had to open up the NES controller and make some space for the additional components. You can see in the pictures on his site that he used a Dremel tool to create a cavity to accommodate the battery. He also severed the on-board IC from the original game controller so that he could tap into the existing buttons with the BlueFruit module.
This extremely simple modification gave him a really nice piece of gaming nostalgia mixed with a bit of anachronistic convenience. Though it is technically finished, he does note that the ugly USB charging cable dangling out the bottom will soon be replaced by a mini-USB female plug, a decision that will really tidy up the controller.