User vashgs has released his new program called GamePadToPc which allows the user to take control of their PC with the Wii U gamepad by taking advantage of the Wii U's web browser. Currently you may only map buttons to keyboard keys, but in future update vashgs has mentioned adding support for mouse control using the Wii U gamepad's analog sticks, as well as streaming the PC's screen to the gamepad, and much more.
GamePadToPC Download
GamePadToPC Release Thread w/ Tutorial