I get stopped all the time by teachers asking where can they apply for a small grant for their classroom. It's no secret that nationally, teachers spend ~$40/month on stuff for their classrooms.
DonorsChoose is a nonprofit web site that connects classroom teachers with a partner. The partner could be an individual, a small group or a business. The teacher fills out a project form along with a wish list of materials. The site is certainly worthy of a look.