You're asking, why should I participate? Besides the fact that it is better to give than receive. Moda3 will have drop off bin at the shop and you will be entered to win a years worth of denim from Volcom.
Not good enough, Moda3 is kicking in a special coupon for all donations - $20 off your next purchase of $100. Why wouldn't you want to participate, it's the holiday season.