Good place to check if you are new to grant writing, and/or if you are you looking for money for something specific for your classroom--art supplies, a digital camera, books.
Links to Other Foundation and Corporate Grants
Didn't find the fourndation grant that you needed above? Browse through thousands of other possibilities here.
State and Federal Grants
Often a good bet if you are you more experienced at grant writing, and/or are you looking for funding for a larger program (e.g. beginning a fine arts academy, developing an after school literacy program for your site).