If you're looking to use gamepads that aren't natively supported by the HTML5 gamepad implementation, and you're working on distributions for Mac/PC/Linux desktop, there are support programs that can enable the usage of all types of gamepads.
For example, use Bluetooth (PS3, Ouya, Gamestick, Logitech gamepads, etc.) gamepads by dropping XB360CE into the executable folder on Windows: code.google.com/p/x360ce
Other platforms have similar support programs, though XB360CE is the only one I can confirm to be 100% working w/ C2 for Node-Webkit export both during testing/development and final executables.