www.prettysporty.com is a great resource for track photography. Photographer Cheryl Treworgy does a terrific job documenting not just sprinters but really does field athletes justice. As a former field guy myself I thank you.
Here's some links to some of her recent events
Duke Invitational 2007 Hammer Throwers
Duke Invitational 2007 Javelin
2007 Division II NCAA Indoor Track & Field Championships - Women's Shot Put