Indoors or outdoors? Daylight or nighttime?
Indoors or night time you will need f2.8 or better, well, at 300mm you can only go to f2.8, but if you can get away with Nikon 200mm a 200 f2 will be better or a Nikon 70-200 2.8 VR1.
Outdoors, daytime, Nikon 300 AFS f4 or Nikon 300 AFS 2.8, Sigma 100-300 f4, maybe the new Sigma 120-300 f2.8 OS?
To be honest though, if you want consistant results, I'd couple any of those with a better body - something with proper AF for high speed action - a D300/D700/D3/D4 (but obviously with the FX bodies you "loose" focal length, but you gain higher ISO capability, negating to some degree the need for greater than f2.8 glass)
Thats not to say that without all of the above you cannot EVER take a photo thats OK, of course you can, I am making the assumption that you want predictable, repeatable performance to get the moment in an image- thats the difference between having cheap vs expensive "pro" gear.