Given the current economic downturn, many artists are seeking new ways to acquire materials for their work. Below are materials programs that may be of use.

Freecycle
The Freecycle Network™ is made up of many individual groups across the globe. It's a grassroots and entirely nonprofit movement of people who are giving (& getting) stuff for free in their own towns.
Website: http://store.freecycle.org/

I Love Schools, Inc.
I Love Schools offers a free donor-matching service for teachers who create Wish Lists of their classroom needs such as equipment, materials, and supplies. Then they're matched with people who donate the items.
Website: www.iloveschools.com/

Materials for the Arts
Run by NYC Dept of Cultural Affairs. Open only to city-based organizations/schools. By appointment only.
Website: www.mfta.org

Materials Resource Center
A community warehouse for materials for arts/education. Non-profit, open to the public, member and non-member shopping. Open 6 days/week.
Website: www.materialresourcecenter.org