Whilst I have made it simple, it's a bit messy and I'll tidy it up soon! The idea was inspired by the way the menu is on this site: http://lab.hakim.se/radar/ and I just had to recreate my own. Absolutely love the effect!
Google Chrome only!!!
Move mouse left/right to rotate. Click the right button to decrease fov (field of view), and the left button to increase.
It may be interesting to note that this doesn't use WebGL, all projection and rendering is done with the 2d canvas context.
And RectangleWorld the actual math: http://rectangleworld.com/blog/archives/298