Going to buy a new Wireless Controller for your next Robotics project. Why buy a new one when you can Do-It-Yourself? All you need is an Arduino, an old Joystick with a Gameport (15-pin connector) and a pair of Series 1 xBee Modules.

The explanation of the xBee Configuration and the xBee Packet Description is very well done at the blog.

Transmitter: Joystick + xBee [No additional hardware needed]
Receiver: xBee + Arduino + [your amazing Robot, Car or a Plane!]