@Bas:I've also found that as long as you move back far enough that you can move your arms without going out of the frame  it will pick you up correctly but obviously it's only good if it's an app that only cares about the head and arms.
I've seen that there's an adapter that makes the lens even wider angled than it already is.
http://www.tomsguide.com/us/Kinect-Nyko-Zoom,news-11449.html

Come to think of it, this gadget might my useful for SlackmmasterK's workspace.