I've found the following interesting examples:
http://through-the-interface.typepad.com/through_the_interface/2006/11/linking_circles.html
http://through-the-interface.typepad.com/through_the_interface/2008/08/rolling-back-th.html
http://through-the-interface.typepad.com/through_the_interface/2008/05/an-automatic--3.html