How to find bidders and artists

I am involved with a San Francisco based charity art event called "Skate This Art."  We give skateboards to artists to design and then we auction them off to benefit Roaddawgz, a homeless youth organization.

We are planning for our upcoming event in 2010 and are looking for new ways to reach out to potential artists and bidders.

A DVD and website are already in the works but what are some other ways that we could get new artists and bidders to participate?