I recently implemented a simple historgram backprojection based vision controller. The sample video (below) shows a hand being tracked with the position of the hand influencing the output of the controller. Distance from the camera is calculated using the area of the object being tracked.
Feel free to download the source code with compiled windows binaries. A working OpenCV installation is also required for this demo to function. Visual Studio 6 project files included. Feel free to mail me with any comments you may have.