Lisa Greenleaf lead a spiral waltz at my wedding.  If you are friends with me or Dan Vilter on Facebook he took a video and you could watch it. One of us shares it every January 5th or so.  It's a great video.  Lisa had everyone form a circle around us (bride and groom) she let us start waltzing in the middle before leading all the guests around us in a circle/spiral left, with her only holding one person's hand.  As the circle got smaller and closer to us she inverted the circle and spiraled everyone back out from the center.  Then she told everyone to waltz with their partners. It was a wonderful moment,  it makes a great video and it's really easy to do. Also since it's just walking in a circle it's easy to get everyone up to do it.