Dress Donation
Let your bridesmaids know about The Princess Project, a 100% volunteer effort to provide free prom dresses and accessories to San Francisco Bay Area girls who could not otherwise afford them. While the Princess Project does not accept wedding dresses, they do accept other formal gowns. See their website for details.
Your wedding dress can be donated to Brides Against Breast Cancer/Making Memories Foundation. They sell quality secondhand gowns or new dresses donated by designers. Give them your own gown after the wedding (who really ever wears it again?) and you’ll help raise money for a worthy cause.
One more site to consider: DonateMyDress.org is a national network listing local dress drive donations. Lisa explains what makes Donate My Dress great.