The first four minutes of this Joe Glickman video provides an excellent overview of surfskiing. The rest of the video focuses heavily on the competitive aspect of the sport, but recreational surfskiing is very popular and growing.
Intro to Surfskis and the 2012 US Downwind Championships
(Olympic Sibling to Surfskiing)
Adam Van Koeverden - Canadian Olympic & World Champion
(Single-Bladed, Stability-Loving Cousin to Surfskiing) More about Outrigger Canoeing