The Mulvane shot (landscape orientation) is definately one of my favorites as well. I also love that shot out there (I forget who by -- please post and claim it!) of a tornadic supercell at night near Red Cloud, Nebraska. Basically, he used a fisheye lens to get an entire storm in the shot, from the ground to the anvil top, backlit by lightning. At the very bottom is a tornado. Probably my favorite storm photo of all time -- one of those moments when serendipity intersects with technical know-how to create something great.