Donors Choose is a website where teachers can write a project proposal for ANYTHING they need for their classroom and random donors will sponsor their project.
Verizon Thinkfinity is a free resource for educators, students and parents. Consider it a web portal to a plethora of resources from partner sites like Smithsonian and ReadWriteThink. This site has it all: lesson plans, student interactives, activity sheets and so forth.
Google Docs is the best free resource for education. Google Docs allows students and teachers to collaborate anytime and anywhere on research papers, spreadsheets, presentations and surveys. The web-based tool eliminates compatibility issues encountered with computer based software. Features such as revision history, equation editor, translator and widgets make this tool perfect for all content areas. If your school doesn't have a Google Apps for Education account, teachers can still publish documents from their personal Google Account and have students collaborate on the document without signing in. Google Docs is flexible and is always improving. Awesome tool for teaching and learning!
Dropbox The free downloadable software available at https://www.dropbox.com/ allows users to store files online. Drag a file to your dropbox, sit down at different computer and open your dropbox by either using the icon if it's a your computer or by logging in on the web site. It makes storing and accessing files very simple with no flash drives needed. It installs on PC, Mac or even Linux! Great for students for use between home and school.