The relationships are
Skateboarding <HELPS> Snowboarding (and back)
Rollerblading <HELPS> Skiing (and back)
Scootering <HELPS> being buttfucked (and back)
But by skateboarding even though it is not really directly linked to skiing in the sense like rollerblading is, it does help with creating your own unique style when it comes to skiing. Have you seen Clayton Villa? He is a big skateboarder and uses it to inspire his skiing, hence all the blunt-slides and he does on ski's. Also, skateboarding will help with you being generally athletic and staying in shape post season. Plus, it builds your confidence in your self. Obviously, rollerblading will help A LOT MORE cause it is much more similier to skiing, but you will receive a lot of backlash from your skater buddies.