Today I shot Sharon vs. Canton in the state soccer playoffs. Using a little Strobist ingenuity (and my new Pocketwizards), I bungee corded a SB-80DX with 1/2 CTO gel on the football goal post (top photo) to add a little light to a quickly darkening second half.
Also, it's amazing what a little light will do in terms of noise. The second image is at ISO 1600 on my D200, and there's almost no noise. Proof again, that noise is directly related to exposure.
I shot 700 images at the game (which Sharon won 4-2) and only used the strobe for probably 30-40 of them, but I feel like it's the little thing that make your images stand out.