I tried to get some acceptable shots of people snowboarding and sledding.  The local golf course has a great hill and the kids I photographed made a small ramp so they could get some air.  After a bit of experimentation I found that the following was giving me good results. 

1. Pre-focus on slightly in front of the ramp and set the camera to manual focus so nothing changes during the sequence.

2. Set up the shot considering the background.

3. Have the action occur to the right side of the image giving the subject some space to move into.

4. Set the camera to rapid shooting mode.

5. Over expose the image by 0.7 to 1.0 EV.  This compensates for the effect of the snow.

6. Set the camera to Shutter Priority and choose the highest speed before the camera starts to underexpose the shots.

7. Start shooting as the subject moves into the focus zone and continue shooting as they move through it.

I am happy with the results.  The biggest difficulty I had was the position of the sun, which was mostly behind the subject.  The over-exposure helped compensate for this.

Other images from this shoot are here.