Long story short, I have an extra activation code for the Skate Share Pack for anyone who bought the game used:

DTVR-8MKZ-N35L-5LX8

This is for Xbox 360, and North America (not sure if that makes a difference).

No way of knowing if it actually works, so my apologies if it doesn't for some reason. But I assume it does. I bought Skate 3 new, then sold it, then bought it again new recently. Turns out the activation code I used the first time around still works. (okay the story isn't that long )

On the card it says code expires May 11, 2011.

Activate it from the pause menu, go to "Create" and select "Activate Skate Share Pack" and then follow on-screen instructions.

Thought someone could use it. Skate Share Pack goes for $10 I think on the Marketplace.