I have found a cheat for skifree!!!!!
when you see a tree stump backup over it and it will turn into a
shroom(magic mushroom)!

After going off a rainbow jump press side and up(diagnal up) and just before you land press down twice you about 300 points do the same on small bumps but don't press down and crash you get about 100 points. 

Pushing up twice and then just before you land push up again get's alot of points. 

Get a couple hundred points as described in a previous hint, and then jump and press down, and you will get 4 or 5 points each time. It takes a while (a long while), but your points add up, and you can get a high (I think, at least) score. 

When you are almost at the bottom of the You know how the people go up on those lift things go underneath them to get heaps of points. 

If you push 'f' while in the air on a rainbow ramp, then hold down up and left AND right you can score about 800 points on one jump