...you need to practice how to pan:
I got a clear shot of the back three-quarters of this hound, despite the fact that I was shooting at three frames/second. <sarcastic> Awesome... </sarcastic>
This is the second of two photos I took of two black greyhounds running at the 2006 Solvang Streak held during the West Coast Greyhound Gathering (WCGG). This particular hound was in full stretch as it passed by me. The result was disappointing on the one hand, but pretty funny (to me, anyway) on the other.
There are very few opportunities (other than the WCGG) for me to see greyhounds running at speed so I don't get to practice panning much. Well, it's wait 'til next year and try again...
(Shot with my Nikon D200 set to aperture-priority, using a 70-200mm VR zoom at f/6.3 and 1/750th second, ISO 200.)