Donor's Choose is a project where classroom teachers submit ideas to do with their students. A donor can go on and give any amout of money to help the teacher reach his or her goal. My own children have supported projects and they received a thank you card.
The Generation Project
The Generation Project is my friend's non-profit that helps everyday people design projects for classroom children. City Public school teachers can choose from the projects and receive funds for their classrooms. The teacher will then send pictures of the students using the materials that were purchased.