You can sign up to do fanfic/fanart/fanvids all of which will be made available on the anniversary, which also happens to be just about a *week* before the Second Season airs.
So you can pledge to do:
-Fanfic: drabbles, poetry or fics at least 5k, 10k, 25k or 50k words long
-Fanart: regular fanart, comic strips, manips, wallpapers, colorbars, layouts etc.
-Fanvids: …(you get the idea ^__^)
You could think of it as a celebration with lots of fandom presents. And darn it, we need a Supernatural Day on livejournal.
So check out how you can sign up, help out – or if nothing else, add requests to the SPN Fandom Wishlist