Another popular category was water sports, particularly surfing. Here's a prime example from Anatol Just of London. "The photo was taken with my Canon 30D with a Sigma 50-500mm lens, with a monopod. The surfer was a contestant at the Ripcurl Pro Competition that is held in and around Hossegor/France every year." Anatol has frozen the action with a shutter speed of 1/1000th of a second and an aperture of f/5.6.
Kite surfing is a sport that is increasing in popularity, and it's also a great source of exciting action shots, such as this one from regular entrant Myra Stokes of Chesham, UK. Myra's shot was also taken at 1/1000th of a second at f/5.6, on a Nikon D50 with a 30mm lens. The location was Orewa Beach, Auckland, New Zealand.
As at least one reader pointed out, snow is frozen water, so this shot from Daniel Lorber of San Diego, California more-or-less fits the theme, especially since it was shot on the shore of scenic Lake Tahoe. Daniel used the 18-55mm kit lens on his Nikon D60, and an exposure of 1/500th of a second at f/5.6 and 200 ISO, fast enough to freeze most of the action, but leaving a slight blur on the flying snow.